openapi-mcp-generator

What it does

This is a code generator that converts OpenAPI 3.0+ specifications into fully typed MCP servers. Given an OpenAPI spec (local file or URL), it scaffolds a complete Node.js project with TypeScript, Zod validation, and your choice of transport: stdio, web via Hono, or StreamableHTTP. The generated server proxies requests to the original REST API while handling authentication (API keys, Bearer tokens, Basic auth, OAuth2) via environment variables.

Who it's for

Backend engineers and API maintainers who want to expose existing REST APIs to Claude and other MCP clients without writing boilerplate. Teams integrating legacy or third-party APIs into AI workflows.

Common use cases

• Expose a private REST API to Claude Code via a stdio-based MCP server
• Generate a web-based MCP server wrapping a third-party SaaS API, complete with HTML test client
• Automate MCP server creation across multiple OpenAPI specs in a CI/CD pipeline
• Enable AI agents to call internal microservices with automatic validation and auth

Setup pitfalls

• Requires --input (OpenAPI spec path/URL) and --output (directory) flags; --base-url must be set if the spec lacks a servers field.
• Configure auth environment variables (API_KEY, BEARER_TOKEN, etc.) before running the generated server.
• High risk classification: generated code reads and writes the filesystem and makes network calls. Validate the OpenAPI spec, test generated servers in isolated environments, and audit for malicious endpoints.
• Transport choice affects dependencies: web transports require Hono. Review package.json after generation and install only necessary dependencies.