OpenAPI to MCP Generator

The OpenAPI to MCP Generator is a command‑line tool that turns any OpenAPI 3.0+ specification into a fully functional Model Context Protocol (MCP) server. By automating the conversion process, it removes the manual effort required to expose a REST API as an MCP endpoint, allowing AI assistants such as Claude or other MCP clients to call the API with native transport methods (stdio, SSE, StreamableHTTP) while preserving type safety and request validation.

This generator solves the common pain point of integrating legacy or third‑party REST services into modern AI workflows. Developers can keep their existing APIs untouched and simply wrap them with an MCP proxy that validates inputs against the OpenAPI schema, enforces authentication rules, and forwards calls to the original backend. The result is a secure, typed interface that AI agents can consume directly without custom adapters or middleware.

Key capabilities include:

• OpenAPI 3.0+ support: Any compliant spec is parsed and converted, automatically extracting paths, operations, parameters, and security schemes.
• Proxy behavior: Requests received over MCP are forwarded to the original REST endpoint, preserving headers and query parameters while applying runtime validation.
• Authentication handling: API keys, bearer tokens, basic auth, and OAuth2 are supported via environment variables, ensuring that security constraints defined in the OpenAPI spec are respected.
• Zod schema generation: The tool produces Zod validators for request bodies and query parameters, providing immediate runtime safety in TypeScript.
• Multiple transport options: Choose between stdio (ideal for local or embedded agents), SSE over Hono (web‑based clients), or StreamableHTTP, giving flexibility for diverse deployment scenarios.
• Project scaffolding: A complete Node.js project is generated with TypeScript configuration, package metadata, and an entry point, enabling rapid iteration and deployment.
• Built‑in HTML test clients: For web transports, a simple browser interface is included to manually trigger and inspect API calls.

Typical use cases span from internal toolchains—where a company wants AI assistants to query their own microservices—to public APIs that need to be exposed to external agents without rewriting endpoints. By providing a typed, validated MCP server, the generator ensures that AI clients receive consistent, error‑free responses and that developers can maintain a single source of truth (the OpenAPI spec) for both documentation and runtime behavior. This tight coupling between specification, validation, and transport streamlines development, reduces bugs, and accelerates the adoption of AI‑driven automation across an organization.