FastMCP OpenAPI

A simple Model Context Protocol (MCP) server that automatically generates tools from OpenAPI specifications using FastMCP.

Features

• Automatic Tool Generation: Converts OpenAPI endpoints into MCP tools automatically
• Flexible Input: Load OpenAPI specs from URLs or local files
• Simple CLI: Easy-to-use command-line interface with click
• Configurable: Customizable base URL, timeouts, and server names

Installation

Option 1: Direct GitHub URL (Easiest)

uvx git+https://github.com/jfouret/fastmcp-openapi.git --base-url https://api.example.com --openapi-url https://api.example.com/openapi.json

Option 2: Clone and Install

git clone https://github.com/jfouret/fastmcp-openapi.git
cd fastmcp-openapi
uv pip install -e .

Usage

Command Line Options

fastmcp-openapi --help

Required:

• --base-url: Base URL for the API (e.g., https://api.example.com)

OpenAPI Source (one required):

• --openapi-url: URL to fetch the OpenAPI specification from
• --openapi-file: Local path to OpenAPI specification file

Optional:

• --name: Custom name for the MCP server (default: "OpenAPI MCP Server")
• --timeout: Request timeout in seconds (default: 30.0)

Examples

From URL

fastmcp-openapi \
  --base-url https://api.example.com \
  --openapi-url https://api.example.com/openapi.json \
  --name "My API Server"

From Local File

fastmcp-openapi \
  --base-url https://api.example.com \
  --openapi-file ./openapi.json \
  --timeout 60.0

Using uvx (Recommended)

uvx git+https://github.com/jfouret/fastmcp-openapi.git \
  --base-url https://api.example.com \
  --openapi-url https://api.example.com/openapi.json

MCP Configuration

Add to your MCP client configuration:

{
  "mcpServers": {
    "my-api": {
      "command": "uvx",
      "args": [
        "git+https://github.com/jfouret/fastmcp-openapi.git",
        "--base-url", "https://api.example.com",
        "--openapi-url", "https://api.example.com/openapi.json",
        "--name", "My API Server"
      ]
    }
  }
}

How It Works

1. Load OpenAPI Spec: Fetches the OpenAPI specification from a URL or loads from a local file
2. Create HTTP Client: Sets up an HTTP client with the specified base URL
3. Generate Tools: Uses FastMCP's from_openapi() to automatically convert all API endpoints into MCP tools
4. Run Server: Starts the MCP server, making all API endpoints available as tools

Supported OpenAPI Features

FastMCP automatically handles:

• All HTTP Methods: GET, POST, PUT, DELETE, PATCH, etc.
• Path Parameters: Dynamic URL segments
• Query Parameters: URL query strings with proper serialization
• Request Bodies: JSON payloads for POST/PUT requests
• Headers: Custom headers and authentication
• Response Schemas: Type validation and documentation

Authentication

Configure authentication on the HTTP client by setting appropriate headers:

# For APIs requiring Bearer tokens, you can extend the server
# or configure authentication in your environment

Requirements

• Python 3.11+
• FastMCP 2.9.2+
• httpx 0.28.1+
• click 8.2.1+

License

MIT License

Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Submit a pull request

Related Projects

• FastMCP - The underlying MCP framework
• mcp-crawl - MCP server for web content fetching