OpenAPI to MCP server Generator

A command-line tool that generates Model Context Protocol (MCP) server code from OpenAPI specifications. This tool helps you quickly create an MCP server that acts as a bridge between LLMs (Large Language Models) and your API.

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At the beginning

This repo is originally forked from openapi-mcp-generator, and add some additional features:

• Support nested $ref in openapi specifications
• Besides source code, generate MCP server configuration
• Allow client to set log level and send log message to client as notification
• When hit error, send message to stderr
• Support build docker image and guide client to run in docker container (2025/5/8 updated)

Features

• Automatic Tool Generation: Converts each API endpoint in your OpenAPI spec into an MCP tool
• Transport Options: Only supports stdio, for sse you can leveral mcp-proxy
• Complete Project Setup: Generates all necessary files to run an MCP server
• Easy Configuration: Simple environment-based configuration for the generated server

Installation

# Install globally from npm
npm install -g openapi-mcpserver-generator

# Or with yarn
yarn global add openapi-mcpserver-generator

# Or with pnpm
pnpm add -g openapi-mcpserver-generator

Usage

Generate an MCP server from an OpenAPI specification:

openapi-mcpserver-generator --openapi path/to/openapi.json --output /Path/to/output

Command Line Options

| Option | Alias | Description | Default | |--------|-------|-------------|---------| | --openapi | -o | Path or URL to OpenAPI specification | (required) | | --output | -d | Output directory for generated files | ./mcp-server | | --name | -n | Name for the MCP server | openapi-mcp-server | | --version | -v | Version for the MCP server | 1.0.0 | | --transport | -t | Transport mechanism (stdio, websocket, http) | stdio | | --help | -h | Show help information | |

Examples

Generate from a local OpenAPI file:

openapi-mcpserver-generator --openapi ./specs/petstore.json --output ./petstore-mcp

Generate from a remote OpenAPI URL:

openapi-mcpserver-generator --openapi https://petstore3.swagger.io/api/v3/openapi.json --output ./petstore-mcp

Generated Files

The tool generates the following files in the output directory:

• server.js - The main MCP server implementation
• package.json - Dependencies and scripts
• README.md - Documentation for the generated server
• .env.example - Template for environment variables
• types.d.ts - TypeScript type definitions for the API
• tsconfig.json - TypeScript configuration
• Dockerfile - Dockerfile
• .dockerignore - Docker ignore file

Using the Generated Server

After generating your MCP server:

1. Navigate to the generated directory:

   cd my-mcp-server

2. Install dependencies:

   npm install

3. Create an environment file:

   cp .env.example .env

4. Edit .env to set your API base URL and any required headers:

   API_BASE_URL=https://api.example.com
   API_HEADERS=Authorization:Bearer your-token-here

5. Start the server:

   npm start

Requirements

• Node.js 16.x or higher
• npm 7.x or higher

E2E example

Suggest use mcpclihost as MCP host to take a try. This tool(mcpclihost) could support both Azure Openai and deepseek

You can add generated MCP server congiguration like this:

{
  "mcpServers": {
    "petstore-mcp": {
      "command": "/usr/local/bin/node",
      "args": [
        "/Users/lipeng/workspaces/github.com/vincent-pli/openapi-mcpserver-generator/petstore-mcp/server.js",
        "run"
      ]
    }
  }
}

to the ~/.mcp.json(default mcp server configuration path of mcpclihost), then take a try

Security Schemes in Openapi

Openapi 3.0 support 4 security types:

• apiKey: for example:

        "securitySchemes": {
            "my_api_key": {
                "type": "apiKey",
                "name": "api_key",
                "in": "header"
            }
        }

Expect a env param named upper cased MY_API_KEY_{securitySchemes.my_api_key.name}, in this case, it should be: MY_API_KEY_API_KEY defined in .env

• http:

        "securitySchemes": {
            basicAuth: {
               type: "http",
               scheme: "basic"
            }
        }

it try to find BASICAUTH_USERNAME and BASICAUTH_PASSWORD in .env

        "securitySchemes": {
            basicAuth: {
               type: "http",
               scheme: "bearer"
            }
        }

it try to find BASICAUTH_BEARERTOKEN in .env

• oauth2: Because of the complexity of oauth2, cannot handle it automaticly, we suggest manually get the access token, then set it to .env as this:

API_HEADERS=Authorization:Bearer your-access-token-here

• openIdConnect Not support yet

License

Apache 2.0