Which integrations are available for this server?

Enables access to GitHub's API through OpenAPI specifications, allowing AI agents to interact with GitHub resources using dynamically generated tools. Provides integration with LangChain for AI agents to use dynamically generated MCP tools for natural language interaction with APIs defined by OpenAPI specifications. Supports LangGraph integration for building AI agent workflows that can interact with APIs through dynamically generated tools from OpenAPI specifications. Dynamically generates MCP tools from Swagger/OpenAPI specifications (2.0, 3.0.x, 3.1.x), converting API operations into callable tools with full parameter validation and authentication support.

How do I use FastMCP OpenAPI?

1. Click on "Install Server". 2. Wait a few minutes for the server to deploy. Once ready, it will show a "Started" state. 3. In the chat, type @ followed by the MCP server name and your instructions, e.g., "@FastMCP OpenAPI get the list of available pets from the petstore API" That's it! The server will respond to your query, and you can continue using it as needed. Here is a step-by-step guide with screenshots.

FastMCP OpenAPI

A FastMCP wrapper that dynamically generates MCP (Model Context Protocol) tools from OpenAPI specifications.

Quick Start

Prerequisites

Python 3.8+ with pip
Node.js 16+ (for MCP Inspector)
OpenAI API key (for LangChain demos)

Installation

pip install fastmcp-openapi

Basic Usage

# Generate MCP tools from any OpenAPI spec
fastmcp-openapi --spec https://petstore.swagger.io/v2/swagger.json

# With authentication
fastmcp-openapi --spec https://api.example.com/openapi.json --auth-header "Bearer your-token"

# Multiple APIs
fastmcp-openapi --spec api1.json --spec api2.json --spec api3.json

Test with MCP Inspector

# Install MCP Inspector
npm install -g @modelcontextprotocol/inspector

# Test your OpenAPI tools
npx @modelcontextprotocol/inspector fastmcp-openapi --spec examples/simple_api.json

# Test Petstore API with Inspector
npx @modelcontextprotocol/inspector fastmcp-openapi --spec https://petstore.swagger.io/v2/swagger.json --base-url https://petstore.swagger.io/v2

Claude Desktop Integration

Add to your Claude Desktop config:

{
  "mcpServers": {
    "openapi-server": {
      "command": "fastmcp-openapi",
      "args": ["--spec", "https://api.example.com/openapi.json", "--auth-header", "Bearer your-token"]
    }
  }
}

Features

✅ Dynamic Tool Generation: Converts OpenAPI operations to MCP tools automatically
✅ Type Safety: Full parameter validation using OpenAPI schemas
✅ Authentication: Bearer tokens, API keys, Basic auth
✅ Multiple APIs: Load multiple OpenAPI specs in one server
✅ Real-time: Add/remove APIs without restart

Command Line Options

fastmcp-openapi --help

Options:
  --spec TEXT          OpenAPI specification URL or file path (can be used multiple times)
  --name TEXT          Server name (default: "OpenAPI Server")
  --auth-header TEXT   Authorization header (e.g., 'Bearer token123'). Must match order of --spec options.
  --base-url TEXT      Override base URL for API calls. Must match order of --spec options.
  --config TEXT        JSON config file with API specifications
  --transport TEXT     Transport: stdio, streamable-http, sse (default: stdio)
  --port INTEGER       Port for HTTP/SSE transport (default: 8000)
  --debug             Enable debug logging

Programmatic Usage

from fastmcp_openapi import OpenAPIServer

# Create server
server = OpenAPIServer("My API Server")

# Add OpenAPI specs
await server.add_openapi_spec(
    name="petstore",
    spec_url="https://petstore.swagger.io/v2/swagger.json",
    auth_header="Bearer your-token"
)

# Run server
server.run()

Examples

Multiple APIs with Different Auth

# Multiple APIs with different base URLs and auth
fastmcp-openapi \
  --spec https://petstore.swagger.io/v2/swagger.json \
  --spec https://api.github.com/openapi.yaml \
  --spec ./local-api.json \
  --base-url https://petstore.swagger.io/v2 \
  --base-url https://api.github.com \
  --base-url http://localhost:3000 \
  --auth-header "Bearer petstore-token" \
  --auth-header "Bearer github-token" \
  --auth-header "Basic local-auth"

# Each API gets its own tools with prefixes:
# - api_1_getPetById (Petstore)
# - api_2_getUser (GitHub)  
# - api_3_createItem (Local API)

Mixed API Sources

# Combine remote and local APIs
fastmcp-openapi \
  --spec https://petstore.swagger.io/v2/swagger.json \
  --spec examples/simple_api.json \
  --spec https://jsonplaceholder.typicode.com/openapi.json \
  --base-url https://petstore.swagger.io/v2 \
  --base-url http://localhost:8080 \
  --base-url https://jsonplaceholder.typicode.com

# Creates unified MCP server with tools from all APIs

Authenticated API

fastmcp-openapi \
  --spec https://api.example.com/openapi.json \
  --auth-header "Bearer your-oauth-token" \
  --base-url "https://api.example.com/v1"

Development Mode

# HTTP mode for web testing
fastmcp-openapi \
  --spec examples/simple_api.json \
  --transport streamable-http \
  --port 8080 \
  --debug

# SSE mode for MCP Inspector
fastmcp-openapi \
  --spec https://petstore.swagger.io/v2/swagger.json \
  --base-url https://petstore.swagger.io/v2 \
  --transport sse \
  --port 8081 \
  --debug

LangChain Integration

# Install required dependencies
pip install langchain-openai langchain-mcp-adapters langgraph

# Set OpenAI API key
export OPENAI_API_KEY="your-openai-api-key"

# Start FastMCP server with HTTP transport
fastmcp-openapi \
  --spec https://petstore.swagger.io/v2/swagger.json \
  --base-url https://petstore.swagger.io/v2 \
  --transport streamable-http \
  --port 8081

# Run LangChain test (in another terminal)
python test_mcp_langchain.py

The LangChain integration allows AI agents to use the generated MCP tools for natural language interaction with APIs.

How It Works

Load OpenAPI Spec: Fetches and parses OpenAPI/Swagger specifications
Generate Tools: Creates MCP tools for each API operation with proper schemas
Handle Requests: Validates parameters and makes authenticated HTTP requests
Return Results: Formats API responses for AI consumption

Supported Features

✅ OpenAPI 3.0.x, 3.1.x, Swagger 2.0
✅ Path/query parameters, headers, request bodies
✅ Authentication (Bearer, API Key, Basic)
✅ Parameter validation and type checking
✅ Multiple APIs in one server
✅ Multiple transports: stdio, streamable-http, sse
✅ LangChain integration for AI agents
✅ MCP Inspector support for interactive testing

Testing & Examples

Quick Test with Petstore API

# 1. Start server with SSE transport
fastmcp-openapi --spec https://petstore.swagger.io/v2/swagger.json --base-url https://petstore.swagger.io/v2 --transport sse --port 8081

# 2. Test with MCP Inspector (in another terminal)
npx @modelcontextprotocol/inspector fastmcp-openapi --spec https://petstore.swagger.io/v2/swagger.json --base-url https://petstore.swagger.io/v2

# 3. Test with LangChain (requires OPENAI_API_KEY)
python test_mcp_langchain.py

Available Transport Modes

stdio: Standard input/output (default, for Claude Desktop)
streamable-http: HTTP-based transport (for LangChain integration)
sse: Server-Sent Events transport (for MCP Inspector)

Multiple API Management

FastMCP OpenAPI supports combining multiple OpenAPI specifications into a single MCP server, each with their own base URLs and authentication.

Configuration Methods

Method 1: JSON Configuration (Recommended)

Create a JSON config file to clearly define each API:

{
  "apis": [
    {
      "name": "petstore",
      "spec": "https://petstore.swagger.io/v2/swagger.json",
      "base_url": "https://petstore.swagger.io/v2",
      "auth": "Bearer petstore-api-key"
    },
    {
      "name": "simple_api", 
      "spec": "examples/simple_api.json",
      "base_url": "http://localhost:8080"
    }
  ]
}

# Use the config file
fastmcp-openapi --config examples/multi_api_config.json --transport sse --port 8081

Method 2: Command Line Arguments (Positional Matching)

⚠️ Important: Arguments must be in the same order - each --base-url and --auth-header matches the corresponding --spec by position.

# Order matters: spec[0]→base_url[0]→auth[0], spec[1]→base_url[1]→auth[1], etc.
fastmcp-openapi \
  --spec https://petstore.swagger.io/v2/swagger.json \     # Position 0
  --spec examples/simple_api.json \                       # Position 1  
  --spec https://api.github.com/openapi.yaml \            # Position 2
  --base-url https://petstore.swagger.io/v2 \             # Position 0 → spec[0]
  --base-url http://localhost:8080 \                      # Position 1 → spec[1]
  --base-url https://api.github.com \                     # Position 2 → spec[2]
  --auth-header "Bearer petstore-key" \                   # Position 0 → spec[0]
  --auth-header "" \                                      # Position 1 → spec[1] (no auth)
  --auth-header "Bearer github-key"                       # Position 2 → spec[2]

Benefits

Unified Interface: Access multiple APIs through one MCP server
Individual Configuration: Each API can have its own base URL and auth
Tool Namespacing: Tools are automatically prefixed to avoid conflicts
Mixed Sources: Combine remote APIs, local services, and files

Tool Naming Convention

When multiple APIs are loaded, tools are automatically prefixed:

Single API: operationId → getPetById
Multiple APIs: api_name_operationId → petstore_getPetById, github_getUser

Development

git clone <repository>
cd fastmcp-openapi
pip install -e ".[dev]"
pytest

License

MIT License

FastMCP OpenAPI

FastMCP OpenAPI

Quick Start

Prerequisites

Installation

Basic Usage

Test with MCP Inspector

Claude Desktop Integration

Features

Command Line Options

Programmatic Usage

Examples

Multiple APIs with Different Auth

Mixed API Sources

Authenticated API

Development Mode

LangChain Integration

How It Works

Supported Features

Testing & Examples

Quick Test with Petstore API

Available Transport Modes

Multiple API Management

Configuration Methods

Method 1: JSON Configuration (Recommended)

Method 2: Command Line Arguments (Positional Matching)

Benefits

Tool Naming Convention

Development

License

Resources

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