relay-mcp

Relay

Universal OpenAPI ➜ MCP relay server with enterprise authentication.

What is Relay?

Relay converts any OpenAPI/Swagger specification into AI-callable MCP tools. It acts as a bridge between AI assistants and REST APIs, automatically generating tools from API documentation and executing real HTTP requests.

Main Function: Transform any REST API into MCP tools that AI assistants can use directly.

Installation

npm install relay-mcp

Basic Usage

Install and build:

npm install
npm run build

Configure (create .env file):

SWAGGER_SOURCE=url
SWAGGER_URL=https://petstore.swagger.io/v2/swagger.json
AUTH_TYPE=none

Run the server:

npm start

Add to MCP client (e.g., Claude Desktop for stdio):

{
  "mcpServers": {
    "relay": {
      "command": "node",
      "args": ["/path/to/relay/dist/index.js"],
      "env": {
        "SWAGGER_SOURCE": "url",
        "SWAGGER_URL": "https://petstore.swagger.io/v2/swagger.json",
        "AUTH_TYPE": "none",
        "TRANSPORT": "stdio"
      }
    }
  }
}

Or run as a standalone server with SSE/HTTP:

# For SSE transport
TRANSPORT=sse TRANSPORT_PORT=3000 npm start

# For HTTP transport
TRANSPORT=http TRANSPORT_PORT=3000 npm start

Then configure your MCP client to connect to http://localhost:3000/mcp.

Features

Dynamic tool generation from any OpenAPI/Swagger spec
Real HTTP execution with interceptors and structured logging
Auth: API Key (header/query), Bearer, Basic
OpenAPI 2.0 and 3.x support
Multiple transport modes: stdio, SSE (Server-Sent Events), HTTP

Documentation

📚 Documentation Hub - Complete documentation index
🚀 Quick Start Guide - Get up and running quickly
🔧 Setup Instructions - Detailed configuration
📋 Changelog - Version history and updates

License

MIT