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mcp-builder
Guide for creating high-quality MCP (Model Context Protocol) servers that enable LLMs to interact with external services through well-designed tools. Use when building MCP servers to integrate external APIs or services, whether in Python (FastMCP), Node/TypeScript (MCP SDK), or C#/.NET (Microsoft MCP SDK).
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Guide for creating high-quality MCP (Model Context Protocol) servers that enable LLMs to interact with external services through well-designed tools. Use when building MCP servers to integrate external APIs or services, whether in Python (FastMCP), Node/TypeScript (MCP SDK), or C#/.NET (Microsoft MCP SDK).
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---
name: mcp-builder
description: Guide for creating high-quality MCP (Model Context Protocol) servers that enable LLMs to interact with external services through well-designed tools. Use when building MCP servers to integrate external APIs or services, whether in Python (FastMCP), Node/TypeScript (MCP SDK), or C#/.NET (Microsoft MCP SDK).
---
# MCP Server Development Guide
## Overview
Create MCP (Model Context Protocol) servers that enable LLMs to interact with external services through well-designed tools. The quality of an MCP server is measured by how well it enables LLMs to accomplish real-world tasks.
---
## Microsoft MCP Ecosystem
Microsoft provides extensive MCP infrastructure for Azure and Foundry services. Understanding this ecosystem helps you decide whether to build custom servers or leverage existing ones.
### Server Types
| Type | Transport | Use Case | Example |
|------|-----------|----------|---------|
| **Local** | stdio | Desktop apps, single-user, local dev | Azure MCP Server via NPM/Docker |
| **Remote** | Streamable HTTP | Cloud services, multi-tenant, Agent Service | `https://mcp.ai.azure.com` (Foundry) |
### Microsoft MCP Servers
Before building a custom server, check if Microsoft already provides one:
| Server | Type | Description |
|--------|------|-------------|
| **Azure MCP** | Local | 48+ Azure services (Storage, KeyVault, Cosmos, SQL, etc.) |
| **Foundry MCP** | Remote | `https://mcp.ai.azure.com` - Models, deployments, evals, agents |
| **Fabric MCP** | Local | Microsoft Fabric APIs, OneLake, item definitions |
| **Playwright MCP** | Local | Browser automation and testing |
| **GitHub MCP** | Remote | `https://api.githubcopilot.com/mcp` |
**Full ecosystem:** See [🔷 Microsoft MCP Patterns](./reference/microsoft_mcp_patterns.md) for complete server catalog and patterns.
### When to Use Microsoft vs Custom
| Scenario | Recommendation |
|----------|----------------|
| Azure service integration | Use **Azure MCP Server** (48 services covered) |
| AI Foundry agents/evals | Use **Foundry MCP** remote server |
| Custom internal APIs | Build **custom server** (this guide) |
| Third-party SaaS integration | Build **custom server** (this guide) |
| Extending Azure MCP | Follow [Microsoft MCP Patterns](./reference/microsoft_mcp_patterns.md)
---
# Process
## 🚀 High-Level Workflow
Creating a high-quality MCP server involves four main phases:
### Phase 1: Deep Research and Planning
#### 1.1 Understand Modern MCP Design
**API Coverage vs. Workflow Tools:**
Balance comprehensive API endpoint coverage with specialized workflow tools. Workflow tools can be more convenient for specific tasks, while comprehensive coverage gives agents flexibility to compose operations. Performance varies by client—some clients benefit from code execution that combines basic tools, while others work better with higher-level workflows. When uncertain, prioritize comprehensive API coverage.
**Tool Naming and Discoverability:**
Clear, descriptive tool names help agents find the right tools quickly. Use consistent prefixes (e.g., `github_create_issue`, `github_list_repos`) and action-oriented naming.
**Context Management:**
Agents benefit from concise tool descriptions and the ability to filter/paginate results. Design tools that return focused, relevant data. Some clients support code execution which can help agents filter and process data efficiently.
**Actionable Error Messages:**
Error messages should guide agents toward solutions with specific suggestions and next steps.
#### 1.2 Study MCP Protocol Documentation
**Navigate the MCP specification:**
Start with the sitemap to find relevant pages: `https://modelcontextprotocol.io/sitemap.xml`
Then fetch specific pages with `.md` suffix for markdown format (e.g., `https://modelcontextprotocol.io/specification/draft.md`).
Key pages to review:
- Specification overview and architecture
- Transport mechanisms (streamable HTTP, stdio)
- Tool, resource, and prompt definitions
#### 1.3 Study Framework Documentation
**Language Selection:**
| Language | Best For | SDK |
|----------|----------|-----|
| **TypeScript** (recommended) | General MCP servers, broad compatibility | `@modelcontextprotocol/sdk` |
| **Python** | Data/ML pipelines, FastAPI integration | `mcp` (FastMCP) |
| **C#/.NET** | Azure/Microsoft ecosystem, enterprise | `Microsoft.Mcp.Core` |
**Transport Selection:**
| Transport | Use Case | Characteristics |
|-----------|----------|-----------------|
| **Streamable HTTP** | Remote servers, multi-tenant, Agent Service | Stateless, scalable, requires auth |
| **stdio** | Local servers, desktop apps | Simple, single-user, no network |
**Load framework documentation:**
- **MCP Best Practices**: [📋 View Best Practices](./reference/mcp_best_practices.md) - Core guidelines
**For TypeScript (recommended):**
- **TypeScript SDK**: Use WebFetch to load `https://raw.githubusercontent.com/modelcontextprotocol/typescript-sdk/main/README.md`
- [⚡ TypeScript Guide](./reference/node_mcp_server.md) - TypeScript patterns and examples
**For Python:**
- **Python SDK**: Use WebFetch to load `https://raw.githubusercontent.com/modelcontextprotocol/python-sdk/main/README.md`
- [🐍 Python Guide](./reference/python_mcp_server.md) - Python patterns and examples
**For C#/.NET (Microsoft ecosystem):**
- [🔷 Microsoft MCP Patterns](./reference/microsoft_mcp_patterns.md) - C# patterns, Azure MCP architecture, command hierarchy
#### 1.4 Plan Your Implementation
**Understand the API:**
Review the service's API documentation to identify key endpoints, authentication requirements, and data models. Use web search and WebFetch as needed.
**Tool Selection:**
Prioritize comprehensive API coverage. List endpoints to implement, starting with the most common operations.
---
### Phase 2: Implementation
#### 2.1 Set Up Project Structure
See language-specific guides for project setup:
- [⚡ TypeScript Guide](./reference/node_mcp_server.md) - Project structure, package.json, tsconfig.json
- [🐍 Python Guide](./reference/python_mcp_server.md) - Module organization, dependencies
- [🔷 Microsoft MCP Patterns](./reference/microsoft_mcp_patterns.md) - C# project structure, command hierarchy
#### 2.2 Implement Core Infrastructure
Create shared utilities:
- API client with authentication
- Error handling helpers
- Response formatting (JSON/Markdown)
- Pagination support
#### 2.3 Implement Tools
For each tool:
**Input Schema:**
- Use Zod (TypeScript) or Pydantic (Python)
- Include constraints and clear descriptions
- Add examples in field descriptions
**Output Schema:**
- Define `outputSchema` where possible for structured data
- Use `structuredContent` in tool responses (TypeScript SDK feature)
- Helps clients understand and process tool outputs
**Tool Description:**
- Concise summary of functionality
- Parameter descriptions
- Return type schema
**Implementation:**
- Async/await for I/O operations
- Proper error handling with actionable messages
- Support pagination where applicable
- Return both text content and structured data when using modern SDKs
**Annotations:**
- `readOnlyHint`: true/false
- `destructiveHint`: true/false
- `idempotentHint`: true/false
- `openWorldHint`: true/false
---
### Phase 3: Review and Test
#### 3.1 Code Quality
Review for:
- No duplicated code (DRY principle)
- Consistent error handling
- Full type coverage
- Clear tool descriptions
#### 3.2 Build and Test
**TypeScript:**
- Run `npm run build` to verify compilation
- Test with MCP Inspector: `npx @modelcontextprotocol/inspector`
**Python:**
- Verify syntax: `python -m py_compile your_server.py`
- Test with MCP Inspector
See language-specific guides for detailed testing approaches and quality checklists.
---
### Phase 4: Create Evaluations
After implementing your MCP server, create comprehensive evaluations to test its effectiveness.
**Load [✅ Evaluation Guide](./reference/evaluation.md) for complete evaluation guidelines.**
#### 4.1 Understand Evaluation Purpose
Use evaluations to test whether LLMs can effectively use your MCP server to answer realistic, complex questions.
#### 4.2 Create 10 Evaluation Questions
To create effective evaluations, follow the process outlined in the evaluation guide:
1. **Tool Inspection**: List available tools and understand their capabilities
2. **Content Exploration**: Use READ-ONLY operations to explore available data
3. **Question Generation**: Create 10 complex, realistic questions
4. **Answer Verification**: Solve each question yourself to verify answers
#### 4.3 Evaluation Requirements
Ensure each question is:
- **Independent**: Not dependent on other questions
- **Read-only**: Only non-destructive operations required
- **Complex**: Requiring multiple tool calls and deep exploration
- **Realistic**: Based on real use cases humans would care about
- **Verifiable**: Single, clear answer that can be verified by string comparison
- **Stable**: Answer won't change over time
#### 4.4 Output Format
Create an XML file with this structure:
```xml
<evaluation>
<qa_pair>
<question>Find discussions about AI model launches with animal codenames. One model needed a specific safety designation that uses the format ASL-X. What number X was being determined for the model named after a spotted wild cat?</question>
<answer>3</answer>
</qa_pair>
<!-- More qa_pairs... -->
</evaluation>
```
---
# Reference Files
## 📚 Documentation Library
Load these resources as needed during development:
### Core MCP Documentation (Load First)
- **MCP Protocol**: Start with sitemap at `https://modelcontextprotocol.io/sitemap.xml`, then fetch specific pages with `.md` suffix
- [📋 MCP Best Practices](./reference/mcp_best_practices.md) - Universal MCP guidelines including:
- Server and tool naming conventions
- Response format guidelines (JSON vs Markdown)
- Pagination best practices
- Transport selection (streamable HTTP vs stdio)
- Security and error handling standards
### Microsoft MCP Documentation (For Azure/Foundry)
- [🔷 Microsoft MCP Patterns](./reference/microsoft_mcp_patterns.md) - Microsoft-specific patterns including:
- Azure MCP Server architecture (48+ Azure services)
- C#/.NET command implementation patterns
- Remote MCP with Foundry Agent Service
- Authentication (Entra ID, OBO flow, Managed Identity)
- Testing infrastructure with Bicep templates
### SDK Documentation (Load During Phase 1/2)
- **Python SDK**: Fetch from `https://raw.githubusercontent.com/modelcontextprotocol/python-sdk/main/README.md`
- **TypeScript SDK**: Fetch from `https://raw.githubusercontent.com/modelcontextprotocol/typescript-sdk/main/README.md`
- **Microsoft MCP SDK**: See [Microsoft MCP Patterns](./reference/microsoft_mcp_patterns.md) for C#/.NET
### Language-Specific Implementation Guides (Load During Phase 2)
- [🐍 Python Implementation Guide](./reference/python_mcp_server.md) - Complete Python/FastMCP guide with:
- Server initialization patterns
- Pydantic model examples
- Tool registration with `@mcp.tool`
- Complete working examples
- Quality checklist
- [⚡ TypeScript Implementation Guide](./reference/node_mcp_server.md) - Complete TypeScript guide with:
- Project structure
- Zod schema patterns
- Tool registration with `server.registerTool`
- Complete working examples
- Quality checklist
- [🔷 Microsoft MCP Patterns](./reference/microsoft_mcp_patterns.md) - Complete C#/.NET guide with:
- Command hierarchy (BaseCommand → GlobalCommand → SubscriptionCommand)
- Naming conventions (`{Resource}{Operation}Command`)
- Option handling with `.AsRequired()` / `.AsOptional()`
- Azure Functions remote MCP deployment
- Live test patterns with Bicep
### Evaluation Guide (Load During Phase 4)
- [✅ Evaluation Guide](./reference/evaluation.md) - Complete evaluation creation guide with:
- Question creation guidelines
- Answer verification strategies
- XML format specifications
- Example questions and answers
- Running an evaluation with the provided scripts
---
## Referenced Files
> The following files are referenced in this skill and included for context.
### reference/microsoft_mcp_patterns.md
```markdown
# Microsoft MCP Patterns
This document covers patterns from Microsoft's official MCP implementations, including the Azure MCP Server and Foundry MCP services. Use these patterns when building MCP servers that integrate with Azure services or follow Microsoft conventions.
---
## Quick Reference
### Microsoft MCP Ecosystem
| Server | Type | Transport | Description |
|--------|------|-----------|-------------|
| **Azure MCP** | Local | stdio | 48+ Azure services (Storage, KeyVault, Cosmos, SQL, etc.) |
| **Foundry MCP** | Remote | Streamable HTTP | `https://mcp.ai.azure.com` - Models, deployments, evals, agents |
| **Fabric MCP** | Local | stdio | Microsoft Fabric APIs, OneLake, item definitions |
| **Playwright MCP** | Local | stdio | Browser automation and testing |
| **GitHub MCP** | Remote | Streamable HTTP | `https://api.githubcopilot.com/mcp` |
| **Azure DevOps** | Local | stdio | Pipelines, repos, boards |
| **SQL Server** | Local | stdio | SQL queries, schema (`aka.ms/MssqlMcp`) |
| **Microsoft Learn** | Remote | Streamable HTTP | `https://learn.microsoft.com/api/mcp` |
### Distribution Formats
Install Azure MCP Server via your preferred method:
| Format | Package/Command | Best For |
|--------|-----------------|----------|
| **VS Code Extension** | `ms-azuretools.vscode-azure-mcp-server` | VS Code users |
| **NPM** | `npx @azure/mcp@latest` | Node.js environments |
| **.NET Tool** | `dotnet tool install -g Azure.Mcp` | .NET developers |
| **Docker** | `mcr.microsoft.com/azure-sdk/azure-mcp` | Containers |
### Command Naming Convention
```
azmcp <service> <resource> <operation>
Examples:
- azmcp storage blob list
- azmcp keyvault secret get
- azmcp cosmos document create
- azmcp appconfig kv set
```
### C# Command Class Naming
```
{Resource}{Operation}Command
Examples:
- StorageContainerListCommand
- KeyVaultSecretGetCommand
- CosmosDbDatabaseQueryCommand
```
### Tool Metadata Annotations
| Annotation | Purpose | Example Use |
|------------|---------|-------------|
| `Destructive` | Modifies or deletes resources | Delete operations |
| `ReadOnly` | Only reads data, no side effects | List, get operations |
| `Idempotent` | Safe to retry, same result | Create-or-update operations |
| `OpenWorld` | Interacts with external systems | API calls to Azure |
| `Secret` | Handles sensitive data | Key Vault operations |
| `LocalRequired` | Requires local resources | File system operations |
---
## Server Architecture
### Azure MCP Service Coverage (48 Services)
| Category | Services |
|----------|----------|
| **Compute** | App Service, Functions, AKS, Container Registry, Virtual Desktop |
| **Storage** | Blob, File Shares, Cosmos DB, Redis, Managed Lustre |
| **Data** | SQL, PostgreSQL, MySQL, Data Explorer (Kusto), Confidential Ledger |
| **AI/ML** | AI Foundry, Search, Speech, Application Insights |
| **Integration** | Event Grid, Event Hubs, Service Bus, SignalR, Communication Services |
| **Security** | Key Vault, RBAC (Authorization), Policy, Advisor |
| **Management** | Monitor, Resource Health, Workbooks, Quota, Azure Migrate |
| **DevOps** | Load Testing, Grafana, Bicep Schema |
**Full list:** Storage, KeyVault, Cosmos, SQL, Postgres, MySQL, AKS, ACR, AppService, Functions, EventGrid, EventHubs, ServiceBus, SignalR, Search, Speech, Monitor, Advisor, Policy, Authorization, and 28+ more.
### Server Modes
The Azure MCP Server supports multiple operational modes:
| Mode | Description | Use Case |
|------|-------------|----------|
| `namespace` | Default mode, tools organized by service namespace | General use |
| `consolidated` | All tools in a single flat namespace | Simple integrations |
| `all` | Exposes all available tools | Development/testing |
| `single` | Single service only | Focused integrations |
### Configuration Example (mcp.json)
```json
{
"mcpServers": {
"azure": {
"command": "npx",
"args": ["-y", "@azure/mcp@latest", "server", "start"],
"env": {
"AZURE_TENANT_ID": "${AZURE_TENANT_ID}",
"AZURE_CLIENT_ID": "${AZURE_CLIENT_ID}"
}
}
}
}
```
### Server Manifest (server.json)
```json
{
"name": "azure-mcp-server",
"version": "1.0.0",
"description": "MCP server for Azure services",
"capabilities": {
"tools": true,
"resources": false,
"prompts": false
},
"transports": ["stdio"],
"authentication": {
"type": "azure-identity",
"scopes": ["https://management.azure.com/.default"]
}
}
```
---
## Modular Architecture Pattern (C#/.NET)
Microsoft's Azure MCP Server uses a modular "Area" pattern for organizing tools by service domain.
### Command Hierarchy
```
IBaseCommand
└── BaseCommand
└── GlobalCommand<TOptions> # No subscription required
└── SubscriptionCommand<TOptions> # Subscription context
└── Service-specific commands # Azure service operations
```
### IAreaSetup Interface
Each Azure service implements `IAreaSetup` to register its tools:
```csharp
public interface IAreaSetup
{
string Name { get; } // e.g., "storage", "keyvault"
string Title { get; } // e.g., "Azure Storage", "Azure Key Vault"
void ConfigureServices(IServiceCollection services);
void RegisterCommands(CommandGroup rootGroup);
}
```
### Implementation Example
```csharp
public class StorageSetup : IAreaSetup
{
public string Name => "storage";
public string Title => "Azure Storage";
public void ConfigureServices(IServiceCollection services)
{
services.AddSingleton<BlobServiceClientFactory>();
services.AddSingleton<StorageAccountService>();
}
public void RegisterCommands(CommandGroup rootGroup)
{
var storageGroup = rootGroup.AddGroup("storage", "Azure Storage operations");
// Blob operations
var blobGroup = storageGroup.AddGroup("blob", "Blob storage operations");
blobGroup.AddCommand<ListBlobsCommand>("list", "List blobs in a container");
blobGroup.AddCommand<GetBlobCommand>("get", "Get blob content");
blobGroup.AddCommand<UploadBlobCommand>("upload", "Upload a blob");
blobGroup.AddCommand<DeleteBlobCommand>("delete", "Delete a blob");
// Container operations
var containerGroup = storageGroup.AddGroup("container", "Container operations");
containerGroup.AddCommand<ListContainersCommand>("list", "List containers");
containerGroup.AddCommand<CreateContainerCommand>("create", "Create a container");
}
}
```
### Command Implementation
```csharp
public class ListBlobsCommand : ICommand
{
[Option("--account", "Storage account name")]
public string AccountName { get; set; } = string.Empty;
[Option("--container", "Container name")]
public string ContainerName { get; set; } = string.Empty;
[Option("--prefix", "Blob name prefix filter")]
public string? Prefix { get; set; }
[Option("--limit", "Maximum number of results")]
public int Limit { get; set; } = 100;
public ToolMetadata Metadata => new()
{
ReadOnly = true,
OpenWorld = true,
Idempotent = true
};
public async Task<CommandResponse> ExecuteAsync(
IServiceProvider services,
CancellationToken cancellationToken)
{
var factory = services.GetRequiredService<BlobServiceClientFactory>();
var client = factory.CreateClient(AccountName);
var container = client.GetBlobContainerClient(ContainerName);
var blobs = new List<BlobItem>();
await foreach (var blob in container.GetBlobsAsync(prefix: Prefix, cancellationToken: cancellationToken))
{
blobs.Add(blob);
if (blobs.Count >= Limit) break;
}
return CommandResponse.Success(new
{
account = AccountName,
container = ContainerName,
count = blobs.Count,
blobs = blobs.Select(b => new
{
name = b.Name,
size = b.Properties.ContentLength,
lastModified = b.Properties.LastModified,
contentType = b.Properties.ContentType
})
});
}
}
```
### Option Registration Extensions
```csharp
// Required options
command.AddOption("--account")
.AsRequired()
.WithDescription("Storage account name");
// Optional options with defaults
command.AddOption("--limit")
.AsOptional()
.WithDefault(100)
.WithDescription("Maximum results to return");
// Enum options
command.AddOption("--access-tier")
.AsOptional()
.WithValues<AccessTier>()
.WithDescription("Blob access tier");
```
---
## Authentication Patterns
### Azure Identity Credential Chain
Microsoft uses a credential chain that tries multiple authentication methods:
```
1. Environment Variables (AZURE_CLIENT_ID, AZURE_CLIENT_SECRET, AZURE_TENANT_ID)
2. Visual Studio credentials
3. Azure CLI credentials
4. Azure PowerShell credentials
5. Azure Developer CLI credentials
6. Interactive browser (development only)
```
### Environment Variable Controls
| Variable | Purpose |
|----------|---------|
| `AZURE_TOKEN_CREDENTIALS` | Override credential type |
| `AZURE_TENANT_ID` | Azure AD tenant ID |
| `AZURE_CLIENT_ID` | Service principal client ID |
| `AZURE_CLIENT_SECRET` | Service principal secret |
| `AZURE_SUBSCRIPTION_ID` | Default subscription |
### Credential Implementation
```csharp
public class AzureCredentialProvider
{
public TokenCredential GetCredential()
{
var credentialType = Environment.GetEnvironmentVariable("AZURE_TOKEN_CREDENTIALS");
return credentialType?.ToLower() switch
{
"environment" => new EnvironmentCredential(),
"cli" => new AzureCliCredential(),
"managedidentity" => new ManagedIdentityCredential(),
_ => new DefaultAzureCredential(new DefaultAzureCredentialOptions
{
ExcludeInteractiveBrowserCredential = !IsDevelopment(),
ExcludeManagedIdentityCredential = IsDevelopment()
})
};
}
}
```
---
## Error Handling Patterns
### Azure SDK Error Handling
```csharp
public static CommandResponse HandleAzureError(RequestFailedException ex)
{
return ex.Status switch
{
404 => CommandResponse.Error(
$"Resource not found. Verify the resource exists and you have access. " +
$"Details: {ex.Message}"),
403 => CommandResponse.Error(
$"Access denied. Check your permissions and ensure your credentials " +
$"have the required role assignments. Details: {ex.Message}"),
401 => CommandResponse.Error(
$"Authentication failed. Run 'az login' or check your credentials. " +
$"Details: {ex.Message}"),
409 => CommandResponse.Error(
$"Conflict: Resource already exists or is in a conflicting state. " +
$"Details: {ex.Message}"),
429 => CommandResponse.Error(
$"Rate limit exceeded. Wait and retry. " +
$"Details: {ex.Message}"),
_ => CommandResponse.Error(
$"Azure API error (HTTP {ex.Status}): {ex.Message}")
};
}
```
### CommandResponse Pattern
```csharp
public class CommandResponse
{
public bool IsSuccess { get; init; }
public object? Data { get; init; }
public string? Error { get; init; }
public static CommandResponse Success(object data) =>
new() { IsSuccess = true, Data = data };
public static CommandResponse Error(string message) =>
new() { IsSuccess = false, Error = message };
}
```
---
## Tool Metadata Best Practices
### Annotation Guidelines
| Operation Type | Destructive | ReadOnly | Idempotent | OpenWorld |
|----------------|-------------|----------|------------|-----------|
| List/Get | ❌ | ✅ | ✅ | ✅ |
| Create | ❌ | ❌ | ❌ | ✅ |
| Create-or-Update | ❌ | ❌ | ✅ | ✅ |
| Update | ❌ | ❌ | ✅ | ✅ |
| Delete | ✅ | ❌ | ✅ | ✅ |
| Purge (permanent) | ✅ | ❌ | ❌ | ✅ |
### Metadata Implementation
```csharp
public class ToolMetadata
{
/// <summary>
/// Tool may perform destructive operations (delete, purge).
/// Clients should confirm before execution.
/// </summary>
public bool Destructive { get; init; }
/// <summary>
/// Tool only reads data, no side effects.
/// Safe to call without confirmation.
/// </summary>
public bool ReadOnly { get; init; }
/// <summary>
/// Repeated calls with same arguments produce same result.
/// Safe to retry on failure.
/// </summary>
public bool Idempotent { get; init; }
/// <summary>
/// Tool interacts with external systems (Azure APIs).
/// May have latency or availability concerns.
/// </summary>
public bool OpenWorld { get; init; }
/// <summary>
/// Tool handles sensitive data (secrets, keys, credentials).
/// Output should be treated as confidential.
/// </summary>
public bool Secret { get; init; }
/// <summary>
/// Tool requires local resources (file system, environment).
/// May not work in all execution contexts.
/// </summary>
public bool LocalRequired { get; init; }
}
```
---
## Remote MCP with Azure Functions
### Initialize from Template
```bash
# Python
azd init --template remote-mcp-functions-python -e mcpserver-python
# TypeScript
azd init --template remote-mcp-functions-typescript -e mcpserver-ts
# .NET
azd init --template remote-mcp-functions-dotnet -e mcpserver-dotnet
```
### TypeScript Tool Registration (Azure Functions)
```typescript
import { app, InvocationContext } from '@azure/functions';
export async function mcpToolStorageList(
_toolArguments: unknown,
context: InvocationContext
): Promise<string> {
const args = context.triggerMetadata.mcptoolargs as {
accountName: string;
prefix?: string;
};
// Implementation
const containers = await listContainers(args.accountName, args.prefix);
return JSON.stringify(containers);
}
app.mcpTool('storage_container_list', {
toolName: 'storage_container_list',
description: 'List all containers in an Azure Storage account',
toolProperties: {
accountName: arg.string()
.describe('Storage account name')
.required(),
prefix: arg.string()
.describe('Filter containers by prefix')
.optional()
},
handler: mcpToolStorageList
});
```
### Deploy to Azure
```bash
# Deploy
azd up
# Get endpoint
# https://{function_app_name}.azurewebsites.net/runtime/webhooks/mcp
```
---
## Testing Infrastructure
### Test Structure
```
tools/Azure.Mcp.Tools.{Service}/tests/
├── Azure.Mcp.Tools.{Service}.UnitTests/ # No Azure resources
├── Azure.Mcp.Tools.{Service}.LiveTests/ # Requires Azure
├── test-resources.bicep # Infrastructure template
└── test-resources-post.ps1 # Post-deployment setup
```
### Unit Tests (No Azure Resources)
```csharp
[TestClass]
public class StorageContainerListCommandTests
{
[TestMethod]
public async Task ListContainers_ReturnsExpectedResults()
{
// Arrange
var mockClient = new Mock<BlobServiceClient>();
var command = new StorageContainerListCommand(mockClient.Object);
// Act
var result = await command.ExecuteAsync(new StorageContainerListOptions
{
AccountName = "teststorage"
});
// Assert
Assert.IsNotNull(result);
}
}
```
### Live Tests (Bicep Infrastructure)
```bicep
// test-resources.bicep
param baseName string
param location string = resourceGroup().location
resource storageAccount 'Microsoft.Storage/storageAccounts@2023-01-01' = {
name: '${baseName}storage'
location: location
sku: { name: 'Standard_LRS' }
kind: 'StorageV2'
}
output STORAGE_ACCOUNT_NAME string = storageAccount.name
```
### Running Tests
```bash
# Unit tests only
./eng/scripts/Test-Code.ps1 -UnitTests
# Live tests (deploys Azure resources)
./eng/scripts/Test-Code.ps1 -LiveTests -ServiceDirectory Storage
# Deploy test resources manually
./eng/scripts/Deploy-TestResources.ps1 -ServiceDirectory Storage
```
---
## Engineering Standards
### Code Style Requirements
| Rule | Requirement |
|------|-------------|
| **Constructors** | Use C# primary constructors |
| **JSON** | Use `System.Text.Json` (no Newtonsoft) |
| **Classes** | Make `sealed` when not inherited |
| **Members** | Make `static` when possible |
| **Files** | One class/interface per file |
| **AOT** | All code must be Native AOT compatible |
### AOT Compatibility
```csharp
// GOOD: AOT compatible
[JsonSerializable(typeof(ContainerListResponse))]
internal partial class ContainerJsonContext : JsonSerializerContext { }
// BAD: Reflection-based (not AOT safe)
JsonSerializer.Deserialize<ContainerListResponse>(json); // Avoid
```
### PR Checklist
Before submitting changes to Microsoft MCP:
- [ ] Code builds with `dotnet build`
- [ ] All unit tests pass
- [ ] Live tests pass (if applicable)
- [ ] AOT analysis passes: `./eng/scripts/Analyze-AOT-Compact.ps1`
- [ ] Tool descriptions are clear and specific
- [ ] No hardcoded credentials or endpoints
- [ ] Follows naming conventions
---
## Integration with Foundry Agent Service
### MCP Tool Declaration (Python)
```python
from azure.ai.projects import AIProjectClient
from azure.ai.projects.models import PromptAgentDefinition, MCPTool
mcp_tool = MCPTool(
server_label="azure-storage",
server_url="https://{app}.azurewebsites.net/runtime/webhooks/mcp",
require_approval="always",
allowed_tools=["storage_container_list"],
project_connection_id=connection_name
)
agent = project_client.agents.create_version(
agent_name="storage-agent",
definition=PromptAgentDefinition(
model="gpt-4o-mini",
instructions="Help users manage Azure Storage",
tools=[mcp_tool]
)
)
```
### MCP Tool Declaration (C#)
```csharp
PromptAgentDefinition agentDefinition = new(model: "gpt-4o-mini")
{
Instructions = "Help users manage Azure Storage",
Tools = {
ResponseTool.CreateMcpTool(
serverLabel: "azure-storage",
serverUri: new Uri("https://{app}.azurewebsites.net/runtime/webhooks/mcp"),
toolCallApprovalPolicy: new McpToolCallApprovalPolicy(
GlobalMcpToolCallApprovalPolicy.AlwaysRequireApproval
)
)
}
};
```
### Handling Approval Requests
```python
for item in response.output:
if item.type == "mcp_approval_request" and item.id:
print(f"Tool: {getattr(item, 'name', '<unknown>')}")
print(f"Arguments: {json.dumps(getattr(item, 'arguments', None), indent=2)}")
should_approve = input("Approve? (y/N): ").strip().lower() == "y"
input_list.append(McpApprovalResponse(
type="mcp_approval_response",
approve=should_approve,
approval_request_id=item.id
))
```
---
## When to Use Microsoft MCP vs Custom
### Use Microsoft MCP Servers When:
- ✅ Integrating with Azure services (Storage, KeyVault, Cosmos, etc.)
- ✅ Working with AI Foundry (agents, evaluations, deployments)
- ✅ Need browser automation (Playwright MCP)
- ✅ GitHub integration (GitHub MCP)
- ✅ Microsoft Fabric operations
### Build Custom MCP Servers When:
- ✅ Integrating with non-Microsoft services
- ✅ Custom internal APIs
- ✅ Third-party SaaS integrations
- ✅ Specialized domain logic not covered by existing servers
- ✅ Need to extend Azure MCP with custom tools
### Extending Azure MCP
If you need to add custom tools alongside Azure MCP:
1. **Separate Server**: Create a custom MCP server for your tools
2. **Multi-Server Config**: Configure both servers in mcp.json
3. **Namespace Prefix**: Use distinct prefixes to avoid conflicts
```json
{
"mcpServers": {
"azure": {
"command": "npx",
"args": ["-y", "@azure/mcp@latest", "server", "start"]
},
"custom": {
"command": "node",
"args": ["./dist/custom-mcp-server.js"]
}
}
}
```
---
## Resources
- **Azure MCP Server**: [github.com/microsoft/mcp](https://github.com/microsoft/mcp)
- **MCP Protocol Spec**: [modelcontextprotocol.io](https://modelcontextprotocol.io)
- **Azure Identity**: [Azure SDK Authentication](https://learn.microsoft.com/azure/developer/javascript/sdk/authentication/overview)
- **Foundry Documentation**: [AI Foundry Docs](https://learn.microsoft.com/azure/ai-studio/)
- **Azure MCP Server Docs**: [learn.microsoft.com/azure/developer/azure-mcp-server](https://learn.microsoft.com/azure/developer/azure-mcp-server/)
- **AZD MCP Templates**: [azure.github.io/awesome-azd/?tags=mcp](https://azure.github.io/awesome-azd/?tags=mcp)
### Code Samples
| Sample | Description | Language |
|--------|-------------|----------|
| `remote-mcp-apim-functions-python` | Secure remote MCP with API Management | Python |
| `remote-mcp-functions-python` | Basic Azure Functions MCP | Python |
| `remote-mcp-functions-dotnet` | Azure Functions MCP | C# |
| `remote-mcp-functions-typescript` | Azure Functions MCP | TypeScript |
| `mcp-container-ts` | MCP on Azure Container Apps | TypeScript |
```
### reference/mcp_best_practices.md
```markdown
# MCP Server Best Practices
## Quick Reference
### Server Naming
- **Python**: `{service}_mcp` (e.g., `slack_mcp`)
- **Node/TypeScript**: `{service}-mcp-server` (e.g., `slack-mcp-server`)
- **C#/.NET (Microsoft)**: `{Service}.Mcp.Server` (e.g., `Azure.Mcp.Server`)
### Tool Naming
- Use snake_case with service prefix
- Format: `{service}_{action}_{resource}`
- Example: `slack_send_message`, `github_create_issue`
- **C# Commands**: `{Resource}{Operation}Command` (e.g., `StorageContainerGetCommand`)
### Response Formats
- Support both JSON and Markdown formats
- JSON for programmatic processing
- Markdown for human readability
### Pagination
- Always respect `limit` parameter
- Return `has_more`, `next_offset`, `total_count`
- Default to 20-50 items
### Transport
- **Streamable HTTP**: For remote servers, multi-client scenarios, Agent Service
- **stdio**: For local integrations, command-line tools
- Avoid SSE (deprecated in favor of streamable HTTP)
---
## Remote vs Local MCP Servers
### Remote MCP Servers (Production/Multi-tenant)
Remote servers are hosted in the cloud and accessible via HTTPS. Required for Azure AI Agent Service integration.
**Characteristics:**
- Stateless request handling (no session state)
- Thread-safe command execution
- Transport-agnostic command design
- Authentication required (Entra ID, API keys)
**Hosting Options:**
| Platform | Transport | Auth | Best For |
|----------|-----------|------|----------|
| **Azure Functions** | HTTP streamable | Built-in/Custom | Serverless, auto-scale |
| **Azure Container Apps** | HTTP POST/GET | Custom | Containers, long-running |
| **App Service** | HTTP | Custom | Full control |
**Endpoint formats:**
- Azure Functions: `https://{app}.azurewebsites.net/runtime/webhooks/mcp`
- Foundry MCP: `https://mcp.ai.azure.com`
- GitHub MCP: `https://api.githubcopilot.com/mcp`
### Local MCP Servers
Local servers run as subprocesses communicating via stdio.
**Characteristics:**
- Single-user, single-session
- No network configuration needed
- Simpler authentication (inherit user context)
**Important:** stdio servers must NOT log to stdout (use stderr for logging).
---
## Server Naming Conventions
Follow these standardized naming patterns:
**Python**: Use format `{service}_mcp` (lowercase with underscores)
- Examples: `slack_mcp`, `github_mcp`, `jira_mcp`
**Node/TypeScript**: Use format `{service}-mcp-server` (lowercase with hyphens)
- Examples: `slack-mcp-server`, `github-mcp-server`, `jira-mcp-server`
The name should be general, descriptive of the service being integrated, easy to infer from the task description, and without version numbers.
---
## Tool Naming and Design
### Tool Naming
1. **Use snake_case**: `search_users`, `create_project`, `get_channel_info`
2. **Include service prefix**: Anticipate that your MCP server may be used alongside other MCP servers
- Use `slack_send_message` instead of just `send_message`
- Use `github_create_issue` instead of just `create_issue`
3. **Be action-oriented**: Start with verbs (get, list, search, create, etc.)
4. **Be specific**: Avoid generic names that could conflict with other servers
### Tool Design
- Tool descriptions must narrowly and unambiguously describe functionality
- Descriptions must precisely match actual functionality
- Provide tool annotations (readOnlyHint, destructiveHint, idempotentHint, openWorldHint)
- Keep tool operations focused and atomic
---
## Response Formats
All tools that return data should support multiple formats:
### JSON Format (`response_format="json"`)
- Machine-readable structured data
- Include all available fields and metadata
- Consistent field names and types
- Use for programmatic processing
### Markdown Format (`response_format="markdown"`, typically default)
- Human-readable formatted text
- Use headers, lists, and formatting for clarity
- Convert timestamps to human-readable format
- Show display names with IDs in parentheses
- Omit verbose metadata
---
## Pagination
For tools that list resources:
- **Always respect the `limit` parameter**
- **Implement pagination**: Use `offset` or cursor-based pagination
- **Return pagination metadata**: Include `has_more`, `next_offset`/`next_cursor`, `total_count`
- **Never load all results into memory**: Especially important for large datasets
- **Default to reasonable limits**: 20-50 items is typical
Example pagination response:
```json
{
"total": 150,
"count": 20,
"offset": 0,
"items": [...],
"has_more": true,
"next_offset": 20
}
```
---
## Transport Options
### Streamable HTTP
**Best for**: Remote servers, web services, multi-client scenarios
**Characteristics**:
- Bidirectional communication over HTTP
- Supports multiple simultaneous clients
- Can be deployed as a web service
- Enables server-to-client notifications
**Use when**:
- Serving multiple clients simultaneously
- Deploying as a cloud service
- Integration with web applications
### stdio
**Best for**: Local integrations, command-line tools
**Characteristics**:
- Standard input/output stream communication
- Simple setup, no network configuration needed
- Runs as a subprocess of the client
**Use when**:
- Building tools for local development environments
- Integrating with desktop applications
- Single-user, single-session scenarios
**Note**: stdio servers should NOT log to stdout (use stderr for logging)
### Transport Selection
| Criterion | stdio | Streamable HTTP |
|-----------|-------|-----------------|
| **Deployment** | Local | Remote |
| **Clients** | Single | Multiple |
| **Complexity** | Low | Medium |
| **Real-time** | No | Yes |
---
## Authentication Patterns
### For Remote MCP Servers
Remote MCP servers require authentication. Choose based on your scenario:
| Method | User Context | Best For |
|--------|--------------|----------|
| **API Key** | No | Simple integrations, internal tools |
| **Entra ID (agent identity)** | No | Azure services with shared identity |
| **Entra ID (managed identity)** | No | Azure-hosted servers |
| **OAuth passthrough (OBO)** | Yes | Multi-tenant, user-specific permissions |
### Microsoft Entra ID (Recommended for Azure)
**On-Behalf-Of (OBO) Flow** - Preserves user identity through the call chain:
```
User → Agent Service → MCP Server → Azure Resource
(OBO token) (validates) (user context)
```
**Configuration:**
```
token_url: https://login.microsoftonline.com/{tenantId}/oauth2/v2.0/token
auth_url: https://login.microsoftonline.com/{tenantId}/oauth2/v2.0/authorize
refresh_url: https://login.microsoftonline.com/{tenantId}/oauth2/v2.0/token
```
### DefaultAzureCredential Chain
For servers that need to call Azure APIs, use the credential chain:
1. `EnvironmentCredential` - CI/CD (service principal vars)
2. `VisualStudioCredential` - VS login
3. `AzureCliCredential` - `az login`
4. `AzurePowerShellCredential` - `Connect-AzAccount`
5. `AzureDeveloperCliCredential` - `azd auth login`
6. `InteractiveBrowserCredential` - Fallback
### For Local MCP Servers
Local servers typically inherit the user's authentication context:
- **Azure CLI**: Use `AzureCliCredential` after `az login`
- **Environment Variables**: `AZURE_CLIENT_ID`, `AZURE_CLIENT_SECRET`, `AZURE_TENANT_ID`
- **API Keys**: Store in environment variables, validate on startup
---
## Security Best Practices
### Authentication and Authorization
**OAuth 2.1**:
- Use secure OAuth 2.1 with certificates from recognized authorities
- Validate access tokens before processing requests
- Only accept tokens specifically intended for your server
**API Keys**:
- Store API keys in environment variables, never in code
- Validate keys on server startup
- Provide clear error messages when authentication fails
### Input Validation
- Sanitize file paths to prevent directory traversal
- Validate URLs and external identifiers
- Check parameter sizes and ranges
- Prevent command injection in system calls
- Use schema validation (Pydantic/Zod) for all inputs
### Error Handling
- Don't expose internal errors to clients
- Log security-relevant errors server-side
- Provide helpful but not revealing error messages
- Clean up resources after errors
### DNS Rebinding Protection
For streamable HTTP servers running locally:
- Enable DNS rebinding protection
- Validate the `Origin` header on all incoming connections
- Bind to `127.0.0.1` rather than `0.0.0.0`
---
## Tool Annotations
Provide annotations to help clients understand tool behavior:
| Annotation | Type | Default | Description |
|-----------|------|---------|-------------|
| `readOnlyHint` | boolean | false | Tool does not modify its environment |
| `destructiveHint` | boolean | true | Tool may perform destructive updates |
| `idempotentHint` | boolean | false | Repeated calls with same args have no additional effect |
| `openWorldHint` | boolean | true | Tool interacts with external entities |
**Important**: Annotations are hints, not security guarantees. Clients should not make security-critical decisions based solely on annotations.
---
## Tool Approval Patterns (Agent Service)
When integrating with Azure AI Agent Service, configure approval requirements:
### Approval Configuration
```python
# Always require approval (default - safest)
require_approval = "always"
# Never require approval (trusted tools only)
require_approval = "never"
# Selective approval
require_approval = {"never": ["read_data", "list_items"]} # Skip for read-only
require_approval = {"always": ["delete_resource", "update_config"]} # Require for destructive
```
### Best Practices for Approval
- **Prefer allow-lists** using `allowed_tools` parameter
- **Require approval** for destructive operations (delete, update, create)
- **Skip approval** only for read-only, non-sensitive operations
- **Log all approvals** for audit trails
### Tool Management (Runtime)
```python
# Dynamically manage tools
mcp_tool.allow_tool("search_api_code")
mcp_tool.disallow_tool("delete_resource")
mcp_tool.set_approval_mode("never")
mcp_tool.update_headers("Authorization", "Bearer ...")
```
---
## Tool Quality Validation
Microsoft's MCP evaluator validates tool descriptions for discoverability.
### Quality Criteria
Tool descriptions must:
1. **Rank in top 3** when evaluated against similar tools
2. **Achieve ≥0.4 confidence** in relevance scoring
3. **Narrowly and unambiguously** describe functionality
4. **Precisely match** actual implementation behavior
### Writing Effective Descriptions
**Good:**
```
"List all storage containers in an Azure Storage account. Returns container names,
last modified dates, and public access levels. Requires storage account name."
```
**Bad:**
```
"Gets storage stuff" // Too vague
"Manages containers" // Ambiguous - create? delete? list?
```
### Testing Tool Discoverability
Before deployment, test that your tool descriptions:
- Are selected by the model for relevant queries
- Are NOT selected for unrelated queries
- Don't conflict with similar tools from other servers
---
## Error Handling
- Use standard JSON-RPC error codes
- Report tool errors within result objects (not protocol-level errors)
- Provide helpful, specific error messages with suggested next steps
- Don't expose internal implementation details
- Clean up resources properly on errors
Example error handling:
```typescript
try {
const result = performOperation();
return { content: [{ type: "text", text: result }] };
} catch (error) {
return {
isError: true,
content: [{
type: "text",
text: `Error: ${error.message}. Try using filter='active_only' to reduce results.`
}]
};
}
```
---
## Testing Requirements
Comprehensive testing should cover:
- **Functional testing**: Verify correct execution with valid/invalid inputs
- **Integration testing**: Test interaction with external systems
- **Security testing**: Validate auth, input sanitization, rate limiting
- **Performance testing**: Check behavior under load, timeouts
- **Error handling**: Ensure proper error reporting and cleanup
---
## Documentation Requirements
- Provide clear documentation of all tools and capabilities
- Include working examples (at least 3 per major feature)
- Document security considerations
- Specify required permissions and access levels
- Document rate limits and performance characteristics
```
### reference/node_mcp_server.md
```markdown
# Node/TypeScript MCP Server Implementation Guide
## Overview
This document provides Node/TypeScript-specific best practices and examples for implementing MCP servers using the MCP TypeScript SDK. It covers project structure, server setup, tool registration patterns, input validation with Zod, error handling, and complete working examples.
---
## Quick Reference
### Key Imports
```typescript
import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { StreamableHTTPServerTransport } from "@modelcontextprotocol/sdk/server/streamableHttp.js";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
import express from "express";
import { z } from "zod";
```
### Server Initialization
```typescript
const server = new McpServer({
name: "service-mcp-server",
version: "1.0.0"
});
```
### Tool Registration Pattern
```typescript
server.registerTool(
"tool_name",
{
title: "Tool Display Name",
description: "What the tool does",
inputSchema: { param: z.string() },
outputSchema: { result: z.string() }
},
async ({ param }) => {
const output = { result: `Processed: ${param}` };
return {
content: [{ type: "text", text: JSON.stringify(output) }],
structuredContent: output // Modern pattern for structured data
};
}
);
```
---
## MCP TypeScript SDK
The official MCP TypeScript SDK provides:
- `McpServer` class for server initialization
- `registerTool` method for tool registration
- Zod schema integration for runtime input validation
- Type-safe tool handler implementations
**IMPORTANT - Use Modern APIs Only:**
- **DO use**: `server.registerTool()`, `server.registerResource()`, `server.registerPrompt()`
- **DO NOT use**: Old deprecated APIs such as `server.tool()`, `server.setRequestHandler(ListToolsRequestSchema, ...)`, or manual handler registration
- The `register*` methods provide better type safety, automatic schema handling, and are the recommended approach
See the MCP SDK documentation in the references for complete details.
## Server Naming Convention
Node/TypeScript MCP servers must follow this naming pattern:
- **Format**: `{service}-mcp-server` (lowercase with hyphens)
- **Examples**: `github-mcp-server`, `jira-mcp-server`, `stripe-mcp-server`
The name should be:
- General (not tied to specific features)
- Descriptive of the service/API being integrated
- Easy to infer from the task description
- Without version numbers or dates
## Project Structure
Create the following structure for Node/TypeScript MCP servers:
```
{service}-mcp-server/
├── package.json
├── tsconfig.json
├── README.md
├── src/
│ ├── index.ts # Main entry point with McpServer initialization
│ ├── types.ts # TypeScript type definitions and interfaces
│ ├── tools/ # Tool implementations (one file per domain)
│ ├── services/ # API clients and shared utilities
│ ├── schemas/ # Zod validation schemas
│ └── constants.ts # Shared constants (API_URL, CHARACTER_LIMIT, etc.)
└── dist/ # Built JavaScript files (entry point: dist/index.js)
```
## Tool Implementation
### Tool Naming
Use snake_case for tool names (e.g., "search_users", "create_project", "get_channel_info") with clear, action-oriented names.
**Avoid Naming Conflicts**: Include the service context to prevent overlaps:
- Use "slack_send_message" instead of just "send_message"
- Use "github_create_issue" instead of just "create_issue"
- Use "asana_list_tasks" instead of just "list_tasks"
### Tool Structure
Tools are registered using the `registerTool` method with the following requirements:
- Use Zod schemas for runtime input validation and type safety
- The `description` field must be explicitly provided - JSDoc comments are NOT automatically extracted
- Explicitly provide `title`, `description`, `inputSchema`, and `annotations`
- The `inputSchema` must be a Zod schema object (not a JSON schema)
- Type all parameters and return values explicitly
```typescript
import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { z } from "zod";
const server = new McpServer({
name: "example-mcp",
version: "1.0.0"
});
// Zod schema for input validation
const UserSearchInputSchema = z.object({
query: z.string()
.min(2, "Query must be at least 2 characters")
.max(200, "Query must not exceed 200 characters")
.describe("Search string to match against names/emails"),
limit: z.number()
.int()
.min(1)
.max(100)
.default(20)
.describe("Maximum results to return"),
offset: z.number()
.int()
.min(0)
.default(0)
.describe("Number of results to skip for pagination"),
response_format: z.nativeEnum(ResponseFormat)
.default(ResponseFormat.MARKDOWN)
.describe("Output format: 'markdown' for human-readable or 'json' for machine-readable")
}).strict();
// Type definition from Zod schema
type UserSearchInput = z.infer<typeof UserSearchInputSchema>;
server.registerTool(
"example_search_users",
{
title: "Search Example Users",
description: `Search for users in the Example system by name, email, or team.
This tool searches across all user profiles in the Example platform, supporting partial matches and various search filters. It does NOT create or modify users, only searches existing ones.
Args:
- query (string): Search string to match against names/emails
- limit (number): Maximum results to return, between 1-100 (default: 20)
- offset (number): Number of results to skip for pagination (default: 0)
- response_format ('markdown' | 'json'): Output format (default: 'markdown')
Returns:
For JSON format: Structured data with schema:
{
"total": number, // Total number of matches found
"count": number, // Number of results in this response
"offset": number, // Current pagination offset
"users": [
{
"id": string, // User ID (e.g., "U123456789")
"name": string, // Full name (e.g., "John Doe")
"email": string, // Email address
"team": string, // Team name (optional)
"active": boolean // Whether user is active
}
],
"has_more": boolean, // Whether more results are available
"next_offset": number // Offset for next page (if has_more is true)
}
Examples:
- Use when: "Find all marketing team members" -> params with query="team:marketing"
- Use when: "Search for John's account" -> params with query="john"
- Don't use when: You need to create a user (use example_create_user instead)
Error Handling:
- Returns "Error: Rate limit exceeded" if too many requests (429 status)
- Returns "No users found matching '<query>'" if search returns empty`,
inputSchema: UserSearchInputSchema,
annotations: {
readOnlyHint: true,
destructiveHint: false,
idempotentHint: true,
openWorldHint: true
}
},
async (params: UserSearchInput) => {
try {
// Input validation is handled by Zod schema
// Make API request using validated parameters
const data = await makeApiRequest<any>(
"users/search",
"GET",
undefined,
{
q: params.query,
limit: params.limit,
offset: params.offset
}
);
const users = data.users || [];
const total = data.total || 0;
if (!users.length) {
return {
content: [{
type: "text",
text: `No users found matching '${params.query}'`
}]
};
}
// Prepare structured output
const output = {
total,
count: users.length,
offset: params.offset,
users: users.map((user: any) => ({
id: user.id,
name: user.name,
email: user.email,
...(user.team ? { team: user.team } : {}),
active: user.active ?? true
})),
has_more: total > params.offset + users.length,
...(total > params.offset + users.length ? {
next_offset: params.offset + users.length
} : {})
};
// Format text representation based on requested format
let textContent: string;
if (params.response_format === ResponseFormat.MARKDOWN) {
const lines = [`# User Search Results: '${params.query}'`, "",
`Found ${total} users (showing ${users.length})`, ""];
for (const user of users) {
lines.push(`## ${user.name} (${user.id})`);
lines.push(`- **Email**: ${user.email}`);
if (user.team) lines.push(`- **Team**: ${user.team}`);
lines.push("");
}
textContent = lines.join("\n");
} else {
textContent = JSON.stringify(output, null, 2);
}
return {
content: [{ type: "text", text: textContent }],
structuredContent: output // Modern pattern for structured data
};
} catch (error) {
return {
content: [{
type: "text",
text: handleApiError(error)
}]
};
}
}
);
```
## Zod Schemas for Input Validation
Zod provides runtime type validation:
```typescript
import { z } from "zod";
// Basic schema with validation
const CreateUserSchema = z.object({
name: z.string()
.min(1, "Name is required")
.max(100, "Name must not exceed 100 characters"),
email: z.string()
.email("Invalid email format"),
age: z.number()
.int("Age must be a whole number")
.min(0, "Age cannot be negative")
.max(150, "Age cannot be greater than 150")
}).strict(); // Use .strict() to forbid extra fields
// Enums
enum ResponseFormat {
MARKDOWN = "markdown",
JSON = "json"
}
const SearchSchema = z.object({
response_format: z.nativeEnum(ResponseFormat)
.default(ResponseFormat.MARKDOWN)
.describe("Output format")
});
// Optional fields with defaults
const PaginationSchema = z.object({
limit: z.number()
.int()
.min(1)
.max(100)
.default(20)
.describe("Maximum results to return"),
offset: z.number()
.int()
.min(0)
.default(0)
.describe("Number of results to skip")
});
```
## Response Format Options
Support multiple output formats for flexibility:
```typescript
enum ResponseFormat {
MARKDOWN = "markdown",
JSON = "json"
}
const inputSchema = z.object({
query: z.string(),
response_format: z.nativeEnum(ResponseFormat)
.default(ResponseFormat.MARKDOWN)
.describe("Output format: 'markdown' for human-readable or 'json' for machine-readable")
});
```
**Markdown format**:
- Use headers, lists, and formatting for clarity
- Convert timestamps to human-readable format
- Show display names with IDs in parentheses
- Omit verbose metadata
- Group related information logically
**JSON format**:
- Return complete, structured data suitable for programmatic processing
- Include all available fields and metadata
- Use consistent field names and types
## Pagination Implementation
For tools that list resources:
```typescript
const ListSchema = z.object({
limit: z.number().int().min(1).max(100).default(20),
offset: z.number().int().min(0).default(0)
});
async function listItems(params: z.infer<typeof ListSchema>) {
const data = await apiRequest(params.limit, params.offset);
const response = {
total: data.total,
count: data.items.length,
offset: params.offset,
items: data.items,
has_more: data.total > params.offset + data.items.length,
next_offset: data.total > params.offset + data.items.length
? params.offset + data.items.length
: undefined
};
return JSON.stringify(response, null, 2);
}
```
## Character Limits and Truncation
Add a CHARACTER_LIMIT constant to prevent overwhelming responses:
```typescript
// At module level in constants.ts
export const CHARACTER_LIMIT = 25000; // Maximum response size in characters
async function searchTool(params: SearchInput) {
let result = generateResponse(data);
// Check character limit and truncate if needed
if (result.length > CHARACTER_LIMIT) {
const truncatedData = data.slice(0, Math.max(1, data.length / 2));
response.data = truncatedData;
response.truncated = true;
response.truncation_message =
`Response truncated from ${data.length} to ${truncatedData.length} items. ` +
`Use 'offset' parameter or add filters to see more results.`;
result = JSON.stringify(response, null, 2);
}
return result;
}
```
## Error Handling
Provide clear, actionable error messages:
```typescript
import axios, { AxiosError } from "axios";
function handleApiError(error: unknown): string {
if (error instanceof AxiosError) {
if (error.response) {
switch (error.response.status) {
case 404:
return "Error: Resource not found. Please check the ID is correct.";
case 403:
return "Error: Permission denied. You don't have access to this resource.";
case 429:
return "Error: Rate limit exceeded. Please wait before making more requests.";
default:
return `Error: API request failed with status ${error.response.status}`;
}
} else if (error.code === "ECONNABORTED") {
return "Error: Request timed out. Please try again.";
}
}
return `Error: Unexpected error occurred: ${error instanceof Error ? error.message : String(error)}`;
}
```
## Shared Utilities
Extract common functionality into reusable functions:
```typescript
// Shared API request function
async function makeApiRequest<T>(
endpoint: string,
method: "GET" | "POST" | "PUT" | "DELETE" = "GET",
data?: any,
params?: any
): Promise<T> {
try {
const response = await axios({
method,
url: `${API_BASE_URL}/${endpoint}`,
data,
params,
timeout: 30000,
headers: {
"Content-Type": "application/json",
"Accept": "application/json"
}
});
return response.data;
} catch (error) {
throw error;
}
}
```
## Async/Await Best Practices
Always use async/await for network requests and I/O operations:
```typescript
// Good: Async network request
async function fetchData(resourceId: string): Promise<ResourceData> {
const response = await axios.get(`${API_URL}/resource/${resourceId}`);
return response.data;
}
// Bad: Promise chains
function fetchData(resourceId: string): Promise<ResourceData> {
return axios.get(`${API_URL}/resource/${resourceId}`)
.then(response => response.data); // Harder to read and maintain
}
```
## TypeScript Best Practices
1. **Use Strict TypeScript**: Enable strict mode in tsconfig.json
2. **Define Interfaces**: Create clear interface definitions for all data structures
3. **Avoid `any`**: Use proper types or `unknown` instead of `any`
4. **Zod for Runtime Validation**: Use Zod schemas to validate external data
5. **Type Guards**: Create type guard functions for complex type checking
6. **Error Handling**: Always use try-catch with proper error type checking
7. **Null Safety**: Use optional chaining (`?.`) and nullish coalescing (`??`)
```typescript
// Good: Type-safe with Zod and interfaces
interface UserResponse {
id: string;
name: string;
email: string;
team?: string;
active: boolean;
}
const UserSchema = z.object({
id: z.string(),
name: z.string(),
email: z.string().email(),
team: z.string().optional(),
active: z.boolean()
});
type User = z.infer<typeof UserSchema>;
async function getUser(id: string): Promise<User> {
const data = await apiCall(`/users/${id}`);
return UserSchema.parse(data); // Runtime validation
}
// Bad: Using any
async function getUser(id: string): Promise<any> {
return await apiCall(`/users/${id}`); // No type safety
}
```
## Package Configuration
### package.json
```json
{
"name": "{service}-mcp-server",
"version": "1.0.0",
"description": "MCP server for {Service} API integration",
"type": "module",
"main": "dist/index.js",
"scripts": {
"start": "node dist/index.js",
"dev": "tsx watch src/index.ts",
"build": "tsc",
"clean": "rm -rf dist"
},
"engines": {
"node": ">=18"
},
"dependencies": {
"@modelcontextprotocol/sdk": "^1.6.1",
"axios": "^1.7.9",
"zod": "^3.23.8"
},
"devDependencies": {
"@types/node": "^22.10.0",
"tsx": "^4.19.2",
"typescript": "^5.7.2"
}
}
```
### tsconfig.json
```json
{
"compilerOptions": {
"target": "ES2022",
"module": "Node16",
"moduleResolution": "Node16",
"lib": ["ES2022"],
"outDir": "./dist",
"rootDir": "./src",
"strict": true,
"esModuleInterop": true,
"skipLibCheck": true,
"forceConsistentCasingInFileNames": true,
"declaration": true,
"declarationMap": true,
"sourceMap": true,
"allowSyntheticDefaultImports": true
},
"include": ["src/**/*"],
"exclude": ["node_modules", "dist"]
}
```
## Complete Example
```typescript
#!/usr/bin/env node
/**
* MCP Server for Example Service.
*
* This server provides tools to interact with Example API, including user search,
* project management, and data export capabilities.
*/
import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
import { z } from "zod";
import axios, { AxiosError } from "axios";
// Constants
const API_BASE_URL = "https://api.example.com/v1";
const CHARACTER_LIMIT = 25000;
// Enums
enum ResponseFormat {
MARKDOWN = "markdown",
JSON = "json"
}
// Zod schemas
const UserSearchInputSchema = z.object({
query: z.string()
.min(2, "Query must be at least 2 characters")
.max(200, "Query must not exceed 200 characters")
.describe("Search string to match against names/emails"),
limit: z.number()
.int()
.min(1)
.max(100)
.default(20)
.describe("Maximum results to return"),
offset: z.number()
.int()
.min(0)
.default(0)
.describe("Number of results to skip for pagination"),
response_format: z.nativeEnum(ResponseFormat)
.default(ResponseFormat.MARKDOWN)
.describe("Output format: 'markdown' for human-readable or 'json' for machine-readable")
}).strict();
type UserSearchInput = z.infer<typeof UserSearchInputSchema>;
// Shared utility functions
async function makeApiRequest<T>(
endpoint: string,
method: "GET" | "POST" | "PUT" | "DELETE" = "GET",
data?: any,
params?: any
): Promise<T> {
try {
const response = await axios({
method,
url: `${API_BASE_URL}/${endpoint}`,
data,
params,
timeout: 30000,
headers: {
"Content-Type": "application/json",
"Accept": "application/json"
}
});
return response.data;
} catch (error) {
throw error;
}
}
function handleApiError(error: unknown): string {
if (error instanceof AxiosError) {
if (error.response) {
switch (error.response.status) {
case 404:
return "Error: Resource not found. Please check the ID is correct.";
case 403:
return "Error: Permission denied. You don't have access to this resource.";
case 429:
return "Error: Rate limit exceeded. Please wait before making more requests.";
default:
return `Error: API request failed with status ${error.response.status}`;
}
} else if (error.code === "ECONNABORTED") {
return "Error: Request timed out. Please try again.";
}
}
return `Error: Unexpected error occurred: ${error instanceof Error ? error.message : String(error)}`;
}
// Create MCP server instance
const server = new McpServer({
name: "example-mcp",
version: "1.0.0"
});
// Register tools
server.registerTool(
"example_search_users",
{
title: "Search Example Users",
description: `[Full description as shown above]`,
inputSchema: UserSearchInputSchema,
annotations: {
readOnlyHint: true,
destructiveHint: false,
idempotentHint: true,
openWorldHint: true
}
},
async (params: UserSearchInput) => {
// Implementation as shown above
}
);
// Main function
// For stdio (local):
async function runStdio() {
if (!process.env.EXAMPLE_API_KEY) {
console.error("ERROR: EXAMPLE_API_KEY environment variable is required");
process.exit(1);
}
const transport = new StdioServerTransport();
await server.connect(transport);
console.error("MCP server running via stdio");
}
// For streamable HTTP (remote):
async function runHTTP() {
if (!process.env.EXAMPLE_API_KEY) {
console.error("ERROR: EXAMPLE_API_KEY environment variable is required");
process.exit(1);
}
const app = express();
app.use(express.json());
app.post('/mcp', async (req, res) => {
const transport = new StreamableHTTPServerTransport({
sessionIdGenerator: undefined,
enableJsonResponse: true
});
res.on('close', () => transport.close());
await server.connect(transport);
await transport.handleRequest(req, res, req.body);
});
const port = parseInt(process.env.PORT || '3000');
app.listen(port, () => {
console.error(`MCP server running on http://localhost:${port}/mcp`);
});
}
// Choose transport based on environment
const transport = process.env.TRANSPORT || 'stdio';
if (transport === 'http') {
runHTTP().catch(error => {
console.error("Server error:", error);
process.exit(1);
});
} else {
runStdio().catch(error => {
console.error("Server error:", error);
process.exit(1);
});
}
```
---
## Advanced MCP Features
### Resource Registration
Expose data as resources for efficient, URI-based access:
```typescript
import { ResourceTemplate } from "@modelcontextprotocol/sdk/types.js";
// Register a resource with URI template
server.registerResource(
{
uri: "file://documents/{name}",
name: "Document Resource",
description: "Access documents by name",
mimeType: "text/plain"
},
async (uri: string) => {
// Extract parameter from URI
const match = uri.match(/^file:\/\/documents\/(.+)$/);
if (!match) {
throw new Error("Invalid URI format");
}
const documentName = match[1];
const content = await loadDocument(documentName);
return {
contents: [{
uri,
mimeType: "text/plain",
text: content
}]
};
}
);
// List available resources dynamically
server.registerResourceList(async () => {
const documents = await getAvailableDocuments();
return {
resources: documents.map(doc => ({
uri: `file://documents/${doc.name}`,
name: doc.name,
mimeType: "text/plain",
description: doc.description
}))
};
});
```
**When to use Resources vs Tools:**
- **Resources**: For data access with simple URI-based parameters
- **Tools**: For complex operations requiring validation and business logic
- **Resources**: When data is relatively static or template-based
- **Tools**: When operations have side effects or complex workflows
### Transport Options
The TypeScript SDK supports two main transport mechanisms:
#### Streamable HTTP (Recommended for Remote Servers)
```typescript
import { StreamableHTTPServerTransport } from "@modelcontextprotocol/sdk/server/streamableHttp.js";
import express from "express";
const app = express();
app.use(express.json());
app.post('/mcp', async (req, res) => {
// Create new transport for each request (stateless, prevents request ID collisions)
const transport = new StreamableHTTPServerTransport({
sessionIdGenerator: undefined,
enableJsonResponse: true
});
res.on('close', () => transport.close());
await server.connect(transport);
await transport.handleRequest(req, res, req.body);
});
app.listen(3000);
```
#### stdio (For Local Integrations)
```typescript
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
const transport = new StdioServerTransport();
await server.connect(transport);
```
**Transport selection:**
- **Streamable HTTP**: Web services, remote access, multiple clients
- **stdio**: Command-line tools, local development, subprocess integration
### Notification Support
Notify clients when server state changes:
```typescript
// Notify when tools list changes
server.notification({
method: "notifications/tools/list_changed"
});
// Notify when resources change
server.notification({
method: "notifications/resources/list_changed"
});
```
Use notifications sparingly - only when server capabilities genuinely change.
---
## Code Best Practices
### Code Composability and Reusability
Your implementation MUST prioritize composability and code reuse:
1. **Extract Common Functionality**:
- Create reusable helper functions for operations used across multiple tools
- Build shared API clients for HTTP requests instead of duplicating code
- Centralize error handling logic in utility functions
- Extract business logic into dedicated functions that can be composed
- Extract shared markdown or JSON field selection & formatting functionality
2. **Avoid Duplication**:
- NEVER copy-paste similar code between tools
- If you find yourself writing similar logic twice, extract it into a function
- Common operations like pagination, filtering, field selection, and formatting should be shared
- Authentication/authorization logic should be centralized
## Building and Running
Always build your TypeScript code before running:
```bash
# Build the project
npm run build
# Run the server
npm start
# Development with auto-reload
npm run dev
```
Always ensure `npm run build` completes successfully before considering the implementation complete.
## Quality Checklist
Before finalizing your Node/TypeScript MCP server implementation, ensure:
### Strategic Design
- [ ] Tools enable complete workflows, not just API endpoint wrappers
- [ ] Tool names reflect natural task subdivisions
- [ ] Response formats optimize for agent context efficiency
- [ ] Human-readable identifiers used where appropriate
- [ ] Error messages guide agents toward correct usage
### Implementation Quality
- [ ] FOCUSED IMPLEMENTATION: Most important and valuable tools implemented
- [ ] All tools registered using `registerTool` with complete configuration
- [ ] All tools include `title`, `description`, `inputSchema`, and `annotations`
- [ ] Annotations correctly set (readOnlyHint, destructiveHint, idempotentHint, openWorldHint)
- [ ] All tools use Zod schemas for runtime input validation with `.strict()` enforcement
- [ ] All Zod schemas have proper constraints and descriptive error messages
- [ ] All tools have comprehensive descriptions with explicit input/output types
- [ ] Descriptions include return value examples and complete schema documentation
- [ ] Error messages are clear, actionable, and educational
### TypeScript Quality
- [ ] TypeScript interfaces are defined for all data structures
- [ ] Strict TypeScript is enabled in tsconfig.json
- [ ] No use of `any` type - use `unknown` or proper types instead
- [ ] All async functions have explicit Promise<T> return types
- [ ] Error handling uses proper type guards (e.g., `axios.isAxiosError`, `z.ZodError`)
### Advanced Features (where applicable)
- [ ] Resources registered for appropriate data endpoints
- [ ] Appropriate transport configured (stdio or streamable HTTP)
- [ ] Notifications implemented for dynamic server capabilities
- [ ] Type-safe with SDK interfaces
### Project Configuration
- [ ] Package.json includes all necessary dependencies
- [ ] Build script produces working JavaScript in dist/ directory
- [ ] Main entry point is properly configured as dist/index.js
- [ ] Server name follows format: `{service}-mcp-server`
- [ ] tsconfig.json properly configured with strict mode
### Code Quality
- [ ] Pagination is properly implemented where applicable
- [ ] Large responses check CHARACTER_LIMIT constant and truncate with clear messages
- [ ] Filtering options are provided for potentially large result sets
- [ ] All network operations handle timeouts and connection errors gracefully
- [ ] Common functionality is extracted into reusable functions
- [ ] Return types are consistent across similar operations
### Testing and Build
- [ ] `npm run build` completes successfully without errors
- [ ] dist/index.js created and executable
- [ ] Server runs: `node dist/index.js --help`
- [ ] All imports resolve correctly
- [ ] Sample tool calls work as expected
---
## Related Resources
### Other Language Guides
- **Python**: [Python MCP Server Guide](./python_mcp_server.md) - FastMCP patterns and Pydantic schemas
- **C#/.NET**: [Microsoft MCP Patterns](./microsoft_mcp_patterns.md) - Azure MCP Server architecture, command hierarchy, Foundry integration
### Microsoft-Specific Patterns
If building MCP servers for Azure services or integrating with Foundry Agent Service, see [Microsoft MCP Patterns](./microsoft_mcp_patterns.md) for:
- Azure Functions remote MCP deployment
- Entra ID authentication patterns
- Tool approval and Agent Service integration
- C# command implementation patterns
```
### reference/python_mcp_server.md
```markdown
# Python MCP Server Implementation Guide
## Overview
This document provides Python-specific best practices and examples for implementing MCP servers using the MCP Python SDK. It covers server setup, tool registration patterns, input validation with Pydantic, error handling, and complete working examples.
---
## Quick Reference
### Key Imports
```python
from mcp.server.fastmcp import FastMCP
from pydantic import BaseModel, Field, field_validator, ConfigDict
from typing import Optional, List, Dict, Any
from enum import Enum
import httpx
```
### Server Initialization
```python
mcp = FastMCP("service_mcp")
```
### Tool Registration Pattern
```python
@mcp.tool(name="tool_name", annotations={...})
async def tool_function(params: InputModel) -> str:
# Implementation
pass
```
---
## MCP Python SDK and FastMCP
The official MCP Python SDK provides FastMCP, a high-level framework for building MCP servers. It provides:
- Automatic description and inputSchema generation from function signatures and docstrings
- Pydantic model integration for input validation
- Decorator-based tool registration with `@mcp.tool`
**For complete SDK documentation, use WebFetch to load:**
`https://raw.githubusercontent.com/modelcontextprotocol/python-sdk/main/README.md`
## Server Naming Convention
Python MCP servers must follow this naming pattern:
- **Format**: `{service}_mcp` (lowercase with underscores)
- **Examples**: `github_mcp`, `jira_mcp`, `stripe_mcp`
The name should be:
- General (not tied to specific features)
- Descriptive of the service/API being integrated
- Easy to infer from the task description
- Without version numbers or dates
## Tool Implementation
### Tool Naming
Use snake_case for tool names (e.g., "search_users", "create_project", "get_channel_info") with clear, action-oriented names.
**Avoid Naming Conflicts**: Include the service context to prevent overlaps:
- Use "slack_send_message" instead of just "send_message"
- Use "github_create_issue" instead of just "create_issue"
- Use "asana_list_tasks" instead of just "list_tasks"
### Tool Structure with FastMCP
Tools are defined using the `@mcp.tool` decorator with Pydantic models for input validation:
```python
from pydantic import BaseModel, Field, ConfigDict
from mcp.server.fastmcp import FastMCP
# Initialize the MCP server
mcp = FastMCP("example_mcp")
# Define Pydantic model for input validation
class ServiceToolInput(BaseModel):
'''Input model for service tool operation.'''
model_config = ConfigDict(
str_strip_whitespace=True, # Auto-strip whitespace from strings
validate_assignment=True, # Validate on assignment
extra='forbid' # Forbid extra fields
)
param1: str = Field(..., description="First parameter description (e.g., 'user123', 'project-abc')", min_length=1, max_length=100)
param2: Optional[int] = Field(default=None, description="Optional integer parameter with constraints", ge=0, le=1000)
tags: Optional[List[str]] = Field(default_factory=list, description="List of tags to apply", max_items=10)
@mcp.tool(
name="service_tool_name",
annotations={
"title": "Human-Readable Tool Title",
"readOnlyHint": True, # Tool does not modify environment
"destructiveHint": False, # Tool does not perform destructive operations
"idempotentHint": True, # Repeated calls have no additional effect
"openWorldHint": False # Tool does not interact with external entities
}
)
async def service_tool_name(params: ServiceToolInput) -> str:
'''Tool description automatically becomes the 'description' field.
This tool performs a specific operation on the service. It validates all inputs
using the ServiceToolInput Pydantic model before processing.
Args:
params (ServiceToolInput): Validated input parameters containing:
- param1 (str): First parameter description
- param2 (Optional[int]): Optional parameter with default
- tags (Optional[List[str]]): List of tags
Returns:
str: JSON-formatted response containing operation results
'''
# Implementation here
pass
```
## Pydantic v2 Key Features
- Use `model_config` instead of nested `Config` class
- Use `field_validator` instead of deprecated `validator`
- Use `model_dump()` instead of deprecated `dict()`
- Validators require `@classmethod` decorator
- Type hints are required for validator methods
```python
from pydantic import BaseModel, Field, field_validator, ConfigDict
class CreateUserInput(BaseModel):
model_config = ConfigDict(
str_strip_whitespace=True,
validate_assignment=True
)
name: str = Field(..., description="User's full name", min_length=1, max_length=100)
email: str = Field(..., description="User's email address", pattern=r'^[\w\.-]+@[\w\.-]+\.\w+$')
age: int = Field(..., description="User's age", ge=0, le=150)
@field_validator('email')
@classmethod
def validate_email(cls, v: str) -> str:
if not v.strip():
raise ValueError("Email cannot be empty")
return v.lower()
```
## Response Format Options
Support multiple output formats for flexibility:
```python
from enum import Enum
class ResponseFormat(str, Enum):
'''Output format for tool responses.'''
MARKDOWN = "markdown"
JSON = "json"
class UserSearchInput(BaseModel):
query: str = Field(..., description="Search query")
response_format: ResponseFormat = Field(
default=ResponseFormat.MARKDOWN,
description="Output format: 'markdown' for human-readable or 'json' for machine-readable"
)
```
**Markdown format**:
- Use headers, lists, and formatting for clarity
- Convert timestamps to human-readable format (e.g., "2024-01-15 10:30:00 UTC" instead of epoch)
- Show display names with IDs in parentheses (e.g., "@john.doe (U123456)")
- Omit verbose metadata (e.g., show only one profile image URL, not all sizes)
- Group related information logically
**JSON format**:
- Return complete, structured data suitable for programmatic processing
- Include all available fields and metadata
- Use consistent field names and types
## Pagination Implementation
For tools that list resources:
```python
class ListInput(BaseModel):
limit: Optional[int] = Field(default=20, description="Maximum results to return", ge=1, le=100)
offset: Optional[int] = Field(default=0, description="Number of results to skip for pagination", ge=0)
async def list_items(params: ListInput) -> str:
# Make API request with pagination
data = await api_request(limit=params.limit, offset=params.offset)
# Return pagination info
response = {
"total": data["total"],
"count": len(data["items"]),
"offset": params.offset,
"items": data["items"],
"has_more": data["total"] > params.offset + len(data["items"]),
"next_offset": params.offset + len(data["items"]) if data["total"] > params.offset + len(data["items"]) else None
}
return json.dumps(response, indent=2)
```
## Error Handling
Provide clear, actionable error messages:
```python
def _handle_api_error(e: Exception) -> str:
'''Consistent error formatting across all tools.'''
if isinstance(e, httpx.HTTPStatusError):
if e.response.status_code == 404:
return "Error: Resource not found. Please check the ID is correct."
elif e.response.status_code == 403:
return "Error: Permission denied. You don't have access to this resource."
elif e.response.status_code == 429:
return "Error: Rate limit exceeded. Please wait before making more requests."
return f"Error: API request failed with status {e.response.status_code}"
elif isinstance(e, httpx.TimeoutException):
return "Error: Request timed out. Please try again."
return f"Error: Unexpected error occurred: {type(e).__name__}"
```
## Shared Utilities
Extract common functionality into reusable functions:
```python
# Shared API request function
async def _make_api_request(endpoint: str, method: str = "GET", **kwargs) -> dict:
'''Reusable function for all API calls.'''
async with httpx.AsyncClient() as client:
response = await client.request(
method,
f"{API_BASE_URL}/{endpoint}",
timeout=30.0,
**kwargs
)
response.raise_for_status()
return response.json()
```
## Async/Await Best Practices
Always use async/await for network requests and I/O operations:
```python
# Good: Async network request
async def fetch_data(resource_id: str) -> dict:
async with httpx.AsyncClient() as client:
response = await client.get(f"{API_URL}/resource/{resource_id}")
response.raise_for_status()
return response.json()
# Bad: Synchronous request
def fetch_data(resource_id: str) -> dict:
response = requests.get(f"{API_URL}/resource/{resource_id}") # Blocks
return response.json()
```
## Type Hints
Use type hints throughout:
```python
from typing import Optional, List, Dict, Any
async def get_user(user_id: str) -> Dict[str, Any]:
data = await fetch_user(user_id)
return {"id": data["id"], "name": data["name"]}
```
## Tool Docstrings
Every tool must have comprehensive docstrings with explicit type information:
```python
async def search_users(params: UserSearchInput) -> str:
'''
Search for users in the Example system by name, email, or team.
This tool searches across all user profiles in the Example platform,
supporting partial matches and various search filters. It does NOT
create or modify users, only searches existing ones.
Args:
params (UserSearchInput): Validated input parameters containing:
- query (str): Search string to match against names/emails (e.g., "john", "@example.com", "team:marketing")
- limit (Optional[int]): Maximum results to return, between 1-100 (default: 20)
- offset (Optional[int]): Number of results to skip for pagination (default: 0)
Returns:
str: JSON-formatted string containing search results with the following schema:
Success response:
{
"total": int, # Total number of matches found
"count": int, # Number of results in this response
"offset": int, # Current pagination offset
"users": [
{
"id": str, # User ID (e.g., "U123456789")
"name": str, # Full name (e.g., "John Doe")
"email": str, # Email address (e.g., "[email protected]")
"team": str # Team name (e.g., "Marketing") - optional
}
]
}
Error response:
"Error: <error message>" or "No users found matching '<query>'"
Examples:
- Use when: "Find all marketing team members" -> params with query="team:marketing"
- Use when: "Search for John's account" -> params with query="john"
- Don't use when: You need to create a user (use example_create_user instead)
- Don't use when: You have a user ID and need full details (use example_get_user instead)
Error Handling:
- Input validation errors are handled by Pydantic model
- Returns "Error: Rate limit exceeded" if too many requests (429 status)
- Returns "Error: Invalid API authentication" if API key is invalid (401 status)
- Returns formatted list of results or "No users found matching 'query'"
'''
```
## Complete Example
See below for a complete Python MCP server example:
```python
#!/usr/bin/env python3
'''
MCP Server for Example Service.
This server provides tools to interact with Example API, including user search,
project management, and data export capabilities.
'''
from typing import Optional, List, Dict, Any
from enum import Enum
import httpx
from pydantic import BaseModel, Field, field_validator, ConfigDict
from mcp.server.fastmcp import FastMCP
# Initialize the MCP server
mcp = FastMCP("example_mcp")
# Constants
API_BASE_URL = "https://api.example.com/v1"
# Enums
class ResponseFormat(str, Enum):
'''Output format for tool responses.'''
MARKDOWN = "markdown"
JSON = "json"
# Pydantic Models for Input Validation
class UserSearchInput(BaseModel):
'''Input model for user search operations.'''
model_config = ConfigDict(
str_strip_whitespace=True,
validate_assignment=True
)
query: str = Field(..., description="Search string to match against names/emails", min_length=2, max_length=200)
limit: Optional[int] = Field(default=20, description="Maximum results to return", ge=1, le=100)
offset: Optional[int] = Field(default=0, description="Number of results to skip for pagination", ge=0)
response_format: ResponseFormat = Field(default=ResponseFormat.MARKDOWN, description="Output format")
@field_validator('query')
@classmethod
def validate_query(cls, v: str) -> str:
if not v.strip():
raise ValueError("Query cannot be empty or whitespace only")
return v.strip()
# Shared utility functions
async def _make_api_request(endpoint: str, method: str = "GET", **kwargs) -> dict:
'''Reusable function for all API calls.'''
async with httpx.AsyncClient() as client:
response = await client.request(
method,
f"{API_BASE_URL}/{endpoint}",
timeout=30.0,
**kwargs
)
response.raise_for_status()
return response.json()
def _handle_api_error(e: Exception) -> str:
'''Consistent error formatting across all tools.'''
if isinstance(e, httpx.HTTPStatusError):
if e.response.status_code == 404:
return "Error: Resource not found. Please check the ID is correct."
elif e.response.status_code == 403:
return "Error: Permission denied. You don't have access to this resource."
elif e.response.status_code == 429:
return "Error: Rate limit exceeded. Please wait before making more requests."
return f"Error: API request failed with status {e.response.status_code}"
elif isinstance(e, httpx.TimeoutException):
return "Error: Request timed out. Please try again."
return f"Error: Unexpected error occurred: {type(e).__name__}"
# Tool definitions
@mcp.tool(
name="example_search_users",
annotations={
"title": "Search Example Users",
"readOnlyHint": True,
"destructiveHint": False,
"idempotentHint": True,
"openWorldHint": True
}
)
async def example_search_users(params: UserSearchInput) -> str:
'''Search for users in the Example system by name, email, or team.
[Full docstring as shown above]
'''
try:
# Make API request using validated parameters
data = await _make_api_request(
"users/search",
params={
"q": params.query,
"limit": params.limit,
"offset": params.offset
}
)
users = data.get("users", [])
total = data.get("total", 0)
if not users:
return f"No users found matching '{params.query}'"
# Format response based on requested format
if params.response_format == ResponseFormat.MARKDOWN:
lines = [f"# User Search Results: '{params.query}'", ""]
lines.append(f"Found {total} users (showing {len(users)})")
lines.append("")
for user in users:
lines.append(f"## {user['name']} ({user['id']})")
lines.append(f"- **Email**: {user['email']}")
if user.get('team'):
lines.append(f"- **Team**: {user['team']}")
lines.append("")
return "\n".join(lines)
else:
# Machine-readable JSON format
import json
response = {
"total": total,
"count": len(users),
"offset": params.offset,
"users": users
}
return json.dumps(response, indent=2)
except Exception as e:
return _handle_api_error(e)
if __name__ == "__main__":
mcp.run()
```
---
## Advanced FastMCP Features
### Context Parameter Injection
FastMCP can automatically inject a `Context` parameter into tools for advanced capabilities like logging, progress reporting, resource reading, and user interaction:
```python
from mcp.server.fastmcp import FastMCP, Context
mcp = FastMCP("example_mcp")
@mcp.tool()
async def advanced_search(query: str, ctx: Context) -> str:
'''Advanced tool with context access for logging and progress.'''
# Report progress for long operations
await ctx.report_progress(0.25, "Starting search...")
# Log information for debugging
await ctx.log_info("Processing query", {"query": query, "timestamp": datetime.now()})
# Perform search
results = await search_api(query)
await ctx.report_progress(0.75, "Formatting results...")
# Access server configuration
server_name = ctx.fastmcp.name
return format_results(results)
@mcp.tool()
async def interactive_tool(resource_id: str, ctx: Context) -> str:
'''Tool that can request additional input from users.'''
# Request sensitive information when needed
api_key = await ctx.elicit(
prompt="Please provide your API key:",
input_type="password"
)
# Use the provided key
return await api_call(resource_id, api_key)
```
**Context capabilities:**
- `ctx.report_progress(progress, message)` - Report progress for long operations
- `ctx.log_info(message, data)` / `ctx.log_error()` / `ctx.log_debug()` - Logging
- `ctx.elicit(prompt, input_type)` - Request input from users
- `ctx.fastmcp.name` - Access server configuration
- `ctx.read_resource(uri)` - Read MCP resources
### Resource Registration
Expose data as resources for efficient, template-based access:
```python
@mcp.resource("file://documents/{name}")
async def get_document(name: str) -> str:
'''Expose documents as MCP resources.
Resources are useful for static or semi-static data that doesn't
require complex parameters. They use URI templates for flexible access.
'''
document_path = f"./docs/{name}"
with open(document_path, "r") as f:
return f.read()
@mcp.resource("config://settings/{key}")
async def get_setting(key: str, ctx: Context) -> str:
'''Expose configuration as resources with context.'''
settings = await load_settings()
return json.dumps(settings.get(key, {}))
```
**When to use Resources vs Tools:**
- **Resources**: For data access with simple parameters (URI templates)
- **Tools**: For complex operations with validation and business logic
### Structured Output Types
FastMCP supports multiple return types beyond strings:
```python
from typing import TypedDict
from dataclasses import dataclass
from pydantic import BaseModel
# TypedDict for structured returns
class UserData(TypedDict):
id: str
name: str
email: str
@mcp.tool()
async def get_user_typed(user_id: str) -> UserData:
'''Returns structured data - FastMCP handles serialization.'''
return {"id": user_id, "name": "John Doe", "email": "[email protected]"}
# Pydantic models for complex validation
class DetailedUser(BaseModel):
id: str
name: str
email: str
created_at: datetime
metadata: Dict[str, Any]
@mcp.tool()
async def get_user_detailed(user_id: str) -> DetailedUser:
'''Returns Pydantic model - automatically generates schema.'''
user = await fetch_user(user_id)
return DetailedUser(**user)
```
### Lifespan Management
Initialize resources that persist across requests:
```python
from contextlib import asynccontextmanager
@asynccontextmanager
async def app_lifespan():
'''Manage resources that live for the server's lifetime.'''
# Initialize connections, load config, etc.
db = await connect_to_database()
config = load_configuration()
# Make available to all tools
yield {"db": db, "config": config}
# Cleanup on shutdown
await db.close()
mcp = FastMCP("example_mcp", lifespan=app_lifespan)
@mcp.tool()
async def query_data(query: str, ctx: Context) -> str:
'''Access lifespan resources through context.'''
db = ctx.request_context.lifespan_state["db"]
results = await db.query(query)
return format_results(results)
```
### Transport Options
FastMCP supports two main transport mechanisms:
```python
# stdio transport (for local tools) - default
if __name__ == "__main__":
mcp.run()
# Streamable HTTP transport (for remote servers)
if __name__ == "__main__":
mcp.run(transport="streamable_http", port=8000)
```
**Transport selection:**
- **stdio**: Command-line tools, local integrations, subprocess execution
- **Streamable HTTP**: Web services, remote access, multiple clients
---
## Code Best Practices
### Code Composability and Reusability
Your implementation MUST prioritize composability and code reuse:
1. **Extract Common Functionality**:
- Create reusable helper functions for operations used across multiple tools
- Build shared API clients for HTTP requests instead of duplicating code
- Centralize error handling logic in utility functions
- Extract business logic into dedicated functions that can be composed
- Extract shared markdown or JSON field selection & formatting functionality
2. **Avoid Duplication**:
- NEVER copy-paste similar code between tools
- If you find yourself writing similar logic twice, extract it into a function
- Common operations like pagination, filtering, field selection, and formatting should be shared
- Authentication/authorization logic should be centralized
### Python-Specific Best Practices
1. **Use Type Hints**: Always include type annotations for function parameters and return values
2. **Pydantic Models**: Define clear Pydantic models for all input validation
3. **Avoid Manual Validation**: Let Pydantic handle input validation with constraints
4. **Proper Imports**: Group imports (standard library, third-party, local)
5. **Error Handling**: Use specific exception types (httpx.HTTPStatusError, not generic Exception)
6. **Async Context Managers**: Use `async with` for resources that need cleanup
7. **Constants**: Define module-level constants in UPPER_CASE
## Quality Checklist
Before finalizing your Python MCP server implementation, ensure:
### Strategic Design
- [ ] Tools enable complete workflows, not just API endpoint wrappers
- [ ] Tool names reflect natural task subdivisions
- [ ] Response formats optimize for agent context efficiency
- [ ] Human-readable identifiers used where appropriate
- [ ] Error messages guide agents toward correct usage
### Implementation Quality
- [ ] FOCUSED IMPLEMENTATION: Most important and valuable tools implemented
- [ ] All tools have descriptive names and documentation
- [ ] Return types are consistent across similar operations
- [ ] Error handling is implemented for all external calls
- [ ] Server name follows format: `{service}_mcp`
- [ ] All network operations use async/await
- [ ] Common functionality is extracted into reusable functions
- [ ] Error messages are clear, actionable, and educational
- [ ] Outputs are properly validated and formatted
### Tool Configuration
- [ ] All tools implement 'name' and 'annotations' in the decorator
- [ ] Annotations correctly set (readOnlyHint, destructiveHint, idempotentHint, openWorldHint)
- [ ] All tools use Pydantic BaseModel for input validation with Field() definitions
- [ ] All Pydantic Fields have explicit types and descriptions with constraints
- [ ] All tools have comprehensive docstrings with explicit input/output types
- [ ] Docstrings include complete schema structure for dict/JSON returns
- [ ] Pydantic models handle input validation (no manual validation needed)
### Advanced Features (where applicable)
- [ ] Context injection used for logging, progress, or elicitation
- [ ] Resources registered for appropriate data endpoints
- [ ] Lifespan management implemented for persistent connections
- [ ] Structured output types used (TypedDict, Pydantic models)
- [ ] Appropriate transport configured (stdio or streamable HTTP)
### Code Quality
- [ ] File includes proper imports including Pydantic imports
- [ ] Pagination is properly implemented where applicable
- [ ] Filtering options are provided for potentially large result sets
- [ ] All async functions are properly defined with `async def`
- [ ] HTTP client usage follows async patterns with proper context managers
- [ ] Type hints are used throughout the code
- [ ] Constants are defined at module level in UPPER_CASE
### Testing
- [ ] Server runs successfully: `python your_server.py --help`
- [ ] All imports resolve correctly
- [ ] Sample tool calls work as expected
- [ ] Error scenarios handled gracefully
---
## Related Resources
### Other Language Guides
- **TypeScript**: [Node/TypeScript MCP Server Guide](./node_mcp_server.md) - Zod schemas, Express.js patterns
- **C#/.NET**: [Microsoft MCP Patterns](./microsoft_mcp_patterns.md) - Azure MCP Server architecture, command hierarchy, Foundry integration
### Microsoft-Specific Patterns
If building MCP servers for Azure services or integrating with Foundry Agent Service, see [Microsoft MCP Patterns](./microsoft_mcp_patterns.md) for:
- Azure Functions remote MCP deployment
- Entra ID authentication patterns
- Tool approval and Agent Service integration
- C# command implementation patterns
```
### reference/evaluation.md
```markdown
# MCP Server Evaluation Guide
## Overview
This document provides guidance on creating comprehensive evaluations for MCP servers. Evaluations test whether LLMs can effectively use your MCP server to answer realistic, complex questions using only the tools provided.
---
## Quick Reference
### Evaluation Requirements
- Create 10 human-readable questions
- Questions must be READ-ONLY, INDEPENDENT, NON-DESTRUCTIVE
- Each question requires multiple tool calls (potentially dozens)
- Answers must be single, verifiable values
- Answers must be STABLE (won't change over time)
### Output Format
```xml
<evaluation>
<qa_pair>
<question>Your question here</question>
<answer>Single verifiable answer</answer>
</qa_pair>
</evaluation>
```
---
## Purpose of Evaluations
The measure of quality of an MCP server is NOT how well or comprehensively the server implements tools, but how well these implementations (input/output schemas, docstrings/descriptions, functionality) enable LLMs with no other context and access ONLY to the MCP servers to answer realistic and difficult questions.
## Evaluation Overview
Create 10 human-readable questions requiring ONLY READ-ONLY, INDEPENDENT, NON-DESTRUCTIVE, and IDEMPOTENT operations to answer. Each question should be:
- Realistic
- Clear and concise
- Unambiguous
- Complex, requiring potentially dozens of tool calls or steps
- Answerable with a single, verifiable value that you identify in advance
## Question Guidelines
### Core Requirements
1. **Questions MUST be independent**
- Each question should NOT depend on the answer to any other question
- Should not assume prior write operations from processing another question
2. **Questions MUST require ONLY NON-DESTRUCTIVE AND IDEMPOTENT tool use**
- Should not instruct or require modifying state to arrive at the correct answer
3. **Questions must be REALISTIC, CLEAR, CONCISE, and COMPLEX**
- Must require another LLM to use multiple (potentially dozens of) tools or steps to answer
### Complexity and Depth
4. **Questions must require deep exploration**
- Consider multi-hop questions requiring multiple sub-questions and sequential tool calls
- Each step should benefit from information found in previous questions
5. **Questions may require extensive paging**
- May need paging through multiple pages of results
- May require querying old data (1-2 years out-of-date) to find niche information
- The questions must be DIFFICULT
6. **Questions must require deep understanding**
- Rather than surface-level knowledge
- May pose complex ideas as True/False questions requiring evidence
- May use multiple-choice format where LLM must search different hypotheses
7. **Questions must not be solvable with straightforward keyword search**
- Do not include specific keywords from the target content
- Use synonyms, related concepts, or paraphrases
- Require multiple searches, analyzing multiple related items, extracting context, then deriving the answer
### Tool Testing
8. **Questions should stress-test tool return values**
- May elicit tools returning large JSON objects or lists, overwhelming the LLM
- Should require understanding multiple modalities of data:
- IDs and names
- Timestamps and datetimes (months, days, years, seconds)
- File IDs, names, extensions, and mimetypes
- URLs, GIDs, etc.
- Should probe the tool's ability to return all useful forms of data
9. **Questions should MOSTLY reflect real human use cases**
- The kinds of information retrieval tasks that HUMANS assisted by an LLM would care about
10. **Questions may require dozens of tool calls**
- This challenges LLMs with limited context
- Encourages MCP server tools to reduce information returned
11. **Include ambiguous questions**
- May be ambiguous OR require difficult decisions on which tools to call
- Force the LLM to potentially make mistakes or misinterpret
- Ensure that despite AMBIGUITY, there is STILL A SINGLE VERIFIABLE ANSWER
### Stability
12. **Questions must be designed so the answer DOES NOT CHANGE**
- Do not ask questions that rely on "current state" which is dynamic
- For example, do not count:
- Number of reactions to a post
- Number of replies to a thread
- Number of members in a channel
13. **DO NOT let the MCP server RESTRICT the kinds of questions you create**
- Create challenging and complex questions
- Some may not be solvable with the available MCP server tools
- Questions may require specific output formats (datetime vs. epoch time, JSON vs. MARKDOWN)
- Questions may require dozens of tool calls to complete
## Answer Guidelines
### Verification
1. **Answers must be VERIFIABLE via direct string comparison**
- If the answer can be re-written in many formats, clearly specify the output format in the QUESTION
- Examples: "Use YYYY/MM/DD.", "Respond True or False.", "Answer A, B, C, or D and nothing else."
- Answer should be a single VERIFIABLE value such as:
- User ID, user name, display name, first name, last name
- Channel ID, channel name
- Message ID, string
- URL, title
- Numerical quantity
- Timestamp, datetime
- Boolean (for True/False questions)
- Email address, phone number
- File ID, file name, file extension
- Multiple choice answer
- Answers must not require special formatting or complex, structured output
- Answer will be verified using DIRECT STRING COMPARISON
### Readability
2. **Answers should generally prefer HUMAN-READABLE formats**
- Examples: names, first name, last name, datetime, file name, message string, URL, yes/no, true/false, a/b/c/d
- Rather than opaque IDs (though IDs are acceptable)
- The VAST MAJORITY of answers should be human-readable
### Stability
3. **Answers must be STABLE/STATIONARY**
- Look at old content (e.g., conversations that have ended, projects that have launched, questions answered)
- Create QUESTIONS based on "closed" concepts that will always return the same answer
- Questions may ask to consider a fixed time window to insulate from non-stationary answers
- Rely on context UNLIKELY to change
- Example: if finding a paper name, be SPECIFIC enough so answer is not confused with papers published later
4. **Answers must be CLEAR and UNAMBIGUOUS**
- Questions must be designed so there is a single, clear answer
- Answer can be derived from using the MCP server tools
### Diversity
5. **Answers must be DIVERSE**
- Answer should be a single VERIFIABLE value in diverse modalities and formats
- User concept: user ID, user name, display name, first name, last name, email address, phone number
- Channel concept: channel ID, channel name, channel topic
- Message concept: message ID, message string, timestamp, month, day, year
6. **Answers must NOT be complex structures**
- Not a list of values
- Not a complex object
- Not a list of IDs or strings
- Not natural language text
- UNLESS the answer can be straightforwardly verified using DIRECT STRING COMPARISON
- And can be realistically reproduced
- It should be unlikely that an LLM would return the same list in any other order or format
## Evaluation Process
### Step 1: Documentation Inspection
Read the documentation of the target API to understand:
- Available endpoints and functionality
- If ambiguity exists, fetch additional information from the web
- Parallelize this step AS MUCH AS POSSIBLE
- Ensure each subagent is ONLY examining documentation from the file system or on the web
### Step 2: Tool Inspection
List the tools available in the MCP server:
- Inspect the MCP server directly
- Understand input/output schemas, docstrings, and descriptions
- WITHOUT calling the tools themselves at this stage
### Step 3: Developing Understanding
Repeat steps 1 & 2 until you have a good understanding:
- Iterate multiple times
- Think about the kinds of tasks you want to create
- Refine your understanding
- At NO stage should you READ the code of the MCP server implementation itself
- Use your intuition and understanding to create reasonable, realistic, but VERY challenging tasks
### Step 4: Read-Only Content Inspection
After understanding the API and tools, USE the MCP server tools:
- Inspect content using READ-ONLY and NON-DESTRUCTIVE operations ONLY
- Goal: identify specific content (e.g., users, channels, messages, projects, tasks) for creating realistic questions
- Should NOT call any tools that modify state
- Will NOT read the code of the MCP server implementation itself
- Parallelize this step with individual sub-agents pursuing independent explorations
- Ensure each subagent is only performing READ-ONLY, NON-DESTRUCTIVE, and IDEMPOTENT operations
- BE CAREFUL: SOME TOOLS may return LOTS OF DATA which would cause you to run out of CONTEXT
- Make INCREMENTAL, SMALL, AND TARGETED tool calls for exploration
- In all tool call requests, use the `limit` parameter to limit results (<10)
- Use pagination
### Step 5: Task Generation
After inspecting the content, create 10 human-readable questions:
- An LLM should be able to answer these with the MCP server
- Follow all question and answer guidelines above
## Output Format
Each QA pair consists of a question and an answer. The output should be an XML file with this structure:
```xml
<evaluation>
<qa_pair>
<question>Find the project created in Q2 2024 with the highest number of completed tasks. What is the project name?</question>
<answer>Website Redesign</answer>
</qa_pair>
<qa_pair>
<question>Search for issues labeled as "bug" that were closed in March 2024. Which user closed the most issues? Provide their username.</question>
<answer>sarah_dev</answer>
</qa_pair>
<qa_pair>
<question>Look for pull requests that modified files in the /api directory and were merged between January 1 and January 31, 2024. How many different contributors worked on these PRs?</question>
<answer>7</answer>
</qa_pair>
<qa_pair>
<question>Find the repository with the most stars that was created before 2023. What is the repository name?</question>
<answer>data-pipeline</answer>
</qa_pair>
</evaluation>
```
## Evaluation Examples
### Good Questions
**Example 1: Multi-hop question requiring deep exploration (GitHub MCP)**
```xml
<qa_pair>
<question>Find the repository that was archived in Q3 2023 and had previously been the most forked project in the organization. What was the primary programming language used in that repository?</question>
<answer>Python</answer>
</qa_pair>
```
This question is good because:
- Requires multiple searches to find archived repositories
- Needs to identify which had the most forks before archival
- Requires examining repository details for the language
- Answer is a simple, verifiable value
- Based on historical (closed) data that won't change
**Example 2: Requires understanding context without keyword matching (Project Management MCP)**
```xml
<qa_pair>
<question>Locate the initiative focused on improving customer onboarding that was completed in late 2023. The project lead created a retrospective document after completion. What was the lead's role title at that time?</question>
<answer>Product Manager</answer>
</qa_pair>
```
This question is good because:
- Doesn't use specific project name ("initiative focused on improving customer onboarding")
- Requires finding completed projects from specific timeframe
- Needs to identify the project lead and their role
- Requires understanding context from retrospective documents
- Answer is human-readable and stable
- Based on completed work (won't change)
**Example 3: Complex aggregation requiring multiple steps (Issue Tracker MCP)**
```xml
<qa_pair>
<question>Among all bugs reported in January 2024 that were marked as critical priority, which assignee resolved the highest percentage of their assigned bugs within 48 hours? Provide the assignee's username.</question>
<answer>alex_eng</answer>
</qa_pair>
```
This question is good because:
- Requires filtering bugs by date, priority, and status
- Needs to group by assignee and calculate resolution rates
- Requires understanding timestamps to determine 48-hour windows
- Tests pagination (potentially many bugs to process)
- Answer is a single username
- Based on historical data from specific time period
**Example 4: Requires synthesis across multiple data types (CRM MCP)**
```xml
<qa_pair>
<question>Find the account that upgraded from the Starter to Enterprise plan in Q4 2023 and had the highest annual contract value. What industry does this account operate in?</question>
<answer>Healthcare</answer>
</qa_pair>
```
This question is good because:
- Requires understanding subscription tier changes
- Needs to identify upgrade events in specific timeframe
- Requires comparing contract values
- Must access account industry information
- Answer is simple and verifiable
- Based on completed historical transactions
### Poor Questions
**Example 1: Answer changes over time**
```xml
<qa_pair>
<question>How many open issues are currently assigned to the engineering team?</question>
<answer>47</answer>
</qa_pair>
```
This question is poor because:
- The answer will change as issues are created, closed, or reassigned
- Not based on stable/stationary data
- Relies on "current state" which is dynamic
**Example 2: Too easy with keyword search**
```xml
<qa_pair>
<question>Find the pull request with title "Add authentication feature" and tell me who created it.</question>
<answer>developer123</answer>
</qa_pair>
```
This question is poor because:
- Can be solved with a straightforward keyword search for exact title
- Doesn't require deep exploration or understanding
- No synthesis or analysis needed
**Example 3: Ambiguous answer format**
```xml
<qa_pair>
<question>List all the repositories that have Python as their primary language.</question>
<answer>repo1, repo2, repo3, data-pipeline, ml-tools</answer>
</qa_pair>
```
This question is poor because:
- Answer is a list that could be returned in any order
- Difficult to verify with direct string comparison
- LLM might format differently (JSON array, comma-separated, newline-separated)
- Better to ask for a specific aggregate (count) or superlative (most stars)
## Verification Process
After creating evaluations:
1. **Examine the XML file** to understand the schema
2. **Load each task instruction** and in parallel using the MCP server and tools, identify the correct answer by attempting to solve the task YOURSELF
3. **Flag any operations** that require WRITE or DESTRUCTIVE operations
4. **Accumulate all CORRECT answers** and replace any incorrect answers in the document
5. **Remove any `<qa_pair>`** that require WRITE or DESTRUCTIVE operations
Remember to parallelize solving tasks to avoid running out of context, then accumulate all answers and make changes to the file at the end.
## Tips for Creating Quality Evaluations
1. **Think Hard and Plan Ahead** before generating tasks
2. **Parallelize Where Opportunity Arises** to speed up the process and manage context
3. **Focus on Realistic Use Cases** that humans would actually want to accomplish
4. **Create Challenging Questions** that test the limits of the MCP server's capabilities
5. **Ensure Stability** by using historical data and closed concepts
6. **Verify Answers** by solving the questions yourself using the MCP server tools
7. **Iterate and Refine** based on what you learn during the process
---
# Running Evaluations
After creating your evaluation file, you can use the provided evaluation harness to test your MCP server.
## Setup
1. **Install Dependencies**
```bash
pip install -r scripts/requirements.txt
```
Or install manually:
```bash
pip install anthropic mcp
```
2. **Set API Key**
```bash
export ANTHROPIC_API_KEY=your_api_key_here
```
## Evaluation File Format
Evaluation files use XML format with `<qa_pair>` elements:
```xml
<evaluation>
<qa_pair>
<question>Find the project created in Q2 2024 with the highest number of completed tasks. What is the project name?</question>
<answer>Website Redesign</answer>
</qa_pair>
<qa_pair>
<question>Search for issues labeled as "bug" that were closed in March 2024. Which user closed the most issues? Provide their username.</question>
<answer>sarah_dev</answer>
</qa_pair>
</evaluation>
```
## Running Evaluations
The evaluation script (`scripts/evaluation.py`) supports three transport types:
**Important:**
- **stdio transport**: The evaluation script automatically launches and manages the MCP server process for you. Do not run the server manually.
- **sse/http transports**: You must start the MCP server separately before running the evaluation. The script connects to the already-running server at the specified URL.
### 1. Local STDIO Server
For locally-run MCP servers (script launches the server automatically):
```bash
python scripts/evaluation.py \
-t stdio \
-c python \
-a my_mcp_server.py \
evaluation.xml
```
With environment variables:
```bash
python scripts/evaluation.py \
-t stdio \
-c python \
-a my_mcp_server.py \
-e API_KEY=abc123 \
-e DEBUG=true \
evaluation.xml
```
### 2. Server-Sent Events (SSE)
For SSE-based MCP servers (you must start the server first):
```bash
python scripts/evaluation.py \
-t sse \
-u https://example.com/mcp \
-H "Authorization: Bearer token123" \
-H "X-Custom-Header: value" \
evaluation.xml
```
### 3. HTTP (Streamable HTTP)
For HTTP-based MCP servers (you must start the server first):
```bash
python scripts/evaluation.py \
-t http \
-u https://example.com/mcp \
-H "Authorization: Bearer token123" \
evaluation.xml
```
## Command-Line Options
```
usage: evaluation.py [-h] [-t {stdio,sse,http}] [-m MODEL] [-c COMMAND]
[-a ARGS [ARGS ...]] [-e ENV [ENV ...]] [-u URL]
[-H HEADERS [HEADERS ...]] [-o OUTPUT]
eval_file
positional arguments:
eval_file Path to evaluation XML file
optional arguments:
-h, --help Show help message
-t, --transport Transport type: stdio, sse, or http (default: stdio)
-m, --model Claude model to use (default: claude-3-7-sonnet-20250219)
-o, --output Output file for report (default: print to stdout)
stdio options:
-c, --command Command to run MCP server (e.g., python, node)
-a, --args Arguments for the command (e.g., server.py)
-e, --env Environment variables in KEY=VALUE format
sse/http options:
-u, --url MCP server URL
-H, --header HTTP headers in 'Key: Value' format
```
## Output
The evaluation script generates a detailed report including:
- **Summary Statistics**:
- Accuracy (correct/total)
- Average task duration
- Average tool calls per task
- Total tool calls
- **Per-Task Results**:
- Prompt and expected response
- Actual response from the agent
- Whether the answer was correct (✅/❌)
- Duration and tool call details
- Agent's summary of its approach
- Agent's feedback on the tools
### Save Report to File
```bash
python scripts/evaluation.py \
-t stdio \
-c python \
-a my_server.py \
-o evaluation_report.md \
evaluation.xml
```
## Complete Example Workflow
Here's a complete example of creating and running an evaluation:
1. **Create your evaluation file** (`my_evaluation.xml`):
```xml
<evaluation>
<qa_pair>
<question>Find the user who created the most issues in January 2024. What is their username?</question>
<answer>alice_developer</answer>
</qa_pair>
<qa_pair>
<question>Among all pull requests merged in Q1 2024, which repository had the highest number? Provide the repository name.</question>
<answer>backend-api</answer>
</qa_pair>
<qa_pair>
<question>Find the project that was completed in December 2023 and had the longest duration from start to finish. How many days did it take?</question>
<answer>127</answer>
</qa_pair>
</evaluation>
```
2. **Install dependencies**:
```bash
pip install -r scripts/requirements.txt
export ANTHROPIC_API_KEY=your_api_key
```
3. **Run evaluation**:
```bash
python scripts/evaluation.py \
-t stdio \
-c python \
-a github_mcp_server.py \
-e GITHUB_TOKEN=ghp_xxx \
-o github_eval_report.md \
my_evaluation.xml
```
4. **Review the report** in `github_eval_report.md` to:
- See which questions passed/failed
- Read the agent's feedback on your tools
- Identify areas for improvement
- Iterate on your MCP server design
## Troubleshooting
### Connection Errors
If you get connection errors:
- **STDIO**: Verify the command and arguments are correct
- **SSE/HTTP**: Check the URL is accessible and headers are correct
- Ensure any required API keys are set in environment variables or headers
### Low Accuracy
If many evaluations fail:
- Review the agent's feedback for each task
- Check if tool descriptions are clear and comprehensive
- Verify input parameters are well-documented
- Consider whether tools return too much or too little data
- Ensure error messages are actionable
### Timeout Issues
If tasks are timing out:
- Use a more capable model (e.g., `claude-3-7-sonnet-20250219`)
- Check if tools are returning too much data
- Verify pagination is working correctly
- Consider simplifying complex questions
```