Generate Model Context Protocol (MCP) servers from OpenAPI specifications.

This CLI tool automates the generation of MCP-compatible servers that proxy requests to existing REST APIs—enabling AI agents and other MCP clients to seamlessly interact with your APIs using your choice of transport methods.

• 🔧 OpenAPI 3.0 Support: Converts any OpenAPI 3.0+ spec into an MCP-compatible server.
• 🔁 Proxy Behavior: Proxies calls to your original REST API while validating request structure and security.
• 🔐 Authentication Support: API keys, Bearer tokens (via environment variables or query parameters), Basic auth, and OAuth2 supported.
• 🧪 Zod Validation: Automatically generates Zod schemas from OpenAPI definitions for runtime input validation.
• ⚙️ Typed Server: Fully typed, maintainable TypeScript code output.
• 🔌 Multiple Transports: Communicate over stdio, SSE via Hono, or StreamableHTTP.
• 🧰 Project Scaffold: Generates a complete Node.js project with tsconfig.json, package.json, and entry point.
• 🧪 Built-in HTML Test Clients: Test API interactions visually in your browser (for web-based transports).

npm install -g openapi-mcp-generator

You can also use yarn global add openapi-mcp-generator or pnpm add -g openapi-mcp-generator

# Generate an MCP server (stdio) openapi-mcp-generator --input path/to/openapi.json --output path/to/output/dir # Generate an MCP web server with SSE openapi-mcp-generator --input path/to/openapi.json --output path/to/output/dir --transport=web --port=3000 # Generate an MCP StreamableHTTP server openapi-mcp-generator --input path/to/openapi.json --output path/to/output/dir --transport=streamable-http --port=3000

You can also use this package programmatically in your Node.js applications:

import { getToolsFromOpenApi } from 'openapi-mcp-generator'; // Extract MCP tool definitions from an OpenAPI spec const tools = await getToolsFromOpenApi('./petstore.json'); // With options const filteredTools = await getToolsFromOpenApi('https://example.com/api-spec.json', { baseUrl: 'https://api.example.com', dereference: true, excludeOperationIds: ['deletePet'], filterFn: (tool) => tool.method.toLowerCase() === 'get', });

For full documentation of the programmatic API, see PROGRAMMATIC_API.md.

The generated project includes:

<output_directory>/ ├── .gitignore ├── package.json ├── tsconfig.json ├── .env.example ├── src/ │ ├── index.ts │ └── [transport-specific-files] └── public/ # For web-based transports └── index.html # Test client 

Core dependencies:

• @modelcontextprotocol/sdk - MCP protocol implementation
• axios - HTTP client for API requests
• zod - Runtime validation
• json-schema-to-zod - Convert JSON Schema to Zod
• Transport-specific deps (Hono, uuid, etc.)

Communicates with MCP clients via standard input/output. Ideal for local development or integration with LLM tools.

Launches a fully functional HTTP server with:

• Server-Sent Events (SSE) for bidirectional messaging
• REST endpoint for client → server communication
• In-browser test client UI
• Multi-connection support
• Built with lightweight Hono framework

Implements the MCP StreamableHTTP transport which offers:

• Stateful JSON-RPC over HTTP POST requests
• Session management using HTTP headers
• Proper HTTP response status codes
• Built-in error handling
• Compatibility with MCP StreamableHTTPClientTransport
• In-browser test client UI
• Built with lightweight Hono framework

Configure auth credentials in your environment:

For web-based transports (SSE and StreamableHTTP), you can also provide Bearer tokens directly in the MCP server URL:

# SSE transport with token https://your-mcp-server.com/sse?token=your_bearer_token_here # StreamableHTTP transport with token https://your-mcp-server.com/mcp?token=your_bearer_token_here

This approach provides session-based isolation, ensuring tokens are only accessible within their respective user sessions.

You can control which operations are exposed as MCP tools using a vendor extension flag x-mcp. This extension is supported at the root, path, and operation levels. By default, endpoints are included unless explicitly excluded.

• Extension: x-mcp: true | false
• Default: true (include by default)
• Precedence: operation > path > root (first non-undefined wins)
• CLI option: --default-include false to change default to exclude by default

Examples:

# Optional root-level default x-mcp: true paths: /pets: x-mcp: false # exclude all ops under /pets get: x-mcp: true # include this operation anyway /users/{id}: get: # no x-mcp -> included by default

This uses standard OpenAPI extensions (x-… fields). See the OpenAPI Extensions guide for details.

Note: x-mcp must be a boolean or the strings "true"/"false" (case-insensitive). Other values are ignored in favor of higher-precedence or default behavior.

cd path/to/output/dir npm install # Run in stdio mode npm start # Run in web server mode npm run start:web # Run in StreamableHTTP mode npm run start:http

For web and StreamableHTTP transports, a browser-based test client is automatically generated:

1. Start the server using the appropriate command
2. Open your browser to http://localhost:<port>
3. Use the test client to interact with your MCP server

• Node.js v20 or later

Contributions are welcome!

1. Fork the repo
2. Create a feature branch: git checkout -b feature/amazing-feature
3. Run npm run format.write to format your code
4. Commit your changes: git commit -m "Add amazing feature"
5. Push and open a PR

📌 Repository: github.com/harsha-iiiv/openapi-mcp-generator

MIT License — see LICENSE for full details.