FastAPI MCP Server

A Model Context Protocol (MCP) server that provides comprehensive tools for introspecting and working with FastAPI applications.

Features

🔧 Tools

1. load_fastapi_app - Load a FastAPI application from a module path
2. list_routes - List all routes with optional filtering
3. get_route_details - Get comprehensive details about a specific route
4. get_openapi_schema - Extract the OpenAPI schema
5. list_models - List all Pydantic models used in the app
6. get_model_schema - Get detailed schema for a specific model
7. search_routes - Search routes by query and criteria
8. analyze_dependencies - Analyze dependency injection usage
9. get_route_source - View the source code of route handlers

Installation

pip install -e .

Usage

With Claude Desktop

Add to your claude_desktop_config.json:

{
  "mcpServers": {
    "fastapi": {
      "command": "python",
      "args": [
        "-m",
        "fastapi_mcp_server.server"
      ],
      "cwd": "/path/to/your/fastapi/project"
    }
  }
}

Standalone

# From your FastAPI project directory
python -m fastapi_mcp_server.server

Example Usage

1. Load Your FastAPI App

Tool: load_fastapi_app
Arguments: {"app_path": "main:app"}

2. List All Routes

Tool: list_routes
Arguments: {}

Or with filters:

Tool: list_routes
Arguments: {
  "method_filter": "GET",
  "tag_filter": "users"
}

3. Get Route Details

Tool: get_route_details
Arguments: {
  "path": "/users/{user_id}",
  "method": "GET"
}

4. Search for Routes

Tool: search_routes
Arguments: {
  "query": "authentication",
  "has_auth": true
}

5. View Route Source Code

Tool: get_route_source
Arguments: {
  "path": "/users",
  "method": "POST"
}

6. List All Models

Tool: list_models
Arguments: {}

7. Get Model Schema

Tool: get_model_schema
Arguments: {"model_name": "User"}

8. Get OpenAPI Schema

Tool: get_openapi_schema
Arguments: {}

Or for specific paths:

Tool: get_openapi_schema
Arguments: {
  "include_only": ["/users", "/users/{user_id}"]
}

9. Analyze Dependencies

Tool: analyze_dependencies
Arguments: {}

Example FastAPI App

See example_app.py for a sample FastAPI application to test with.

Use Cases

🔍 API Discovery

• Quickly understand what endpoints exist
• Find routes by functionality or path
• Explore API structure

📚 Documentation Generation

• Extract OpenAPI schemas
• Get detailed parameter information
• View model schemas with examples

🐛 Debugging

• Inspect route configurations
• View dependency injection hierarchy
• Check parameter validations

🔨 Development

• Generate client code from schemas
• Understand existing APIs before modification
• Find all routes using specific models

🧪 Testing

• List all endpoints for test coverage
• Get parameter requirements for test cases
• Validate response models

Requirements

• Python 3.10+
• FastAPI 0.100.0+
• MCP 1.0.0+
• Pydantic 2.0.0+

Contributing

Contributions are welcome! This tool helps developers work more efficiently with FastAPI applications.

License

MIT License - feel free to use in your projects!

Author

Created as part of the FastAPI ecosystem to improve developer experience with AI-assisted development.