fast-mcp

Why we included this project

If your application is built on Ruby and you want large language models to call your own code, Fast MCP gives you a clean way to make that happen. It implements the Model Context Protocol, so you define tools as ordinary Ruby classes and the library handles schema generation and argument validation via Dry-Schema. Resources are exposed the same way, and you can serve the server over STDIO, HTTP, or SSE from any Rack app. A Rails generator scaffolds the folder structure and auto-discovers your subclasses, and request-aware filtering lets you restrict which tools a given call sees based on role or API version. That makes it a practical fit for teams that want models to interact with their real application logic without building custom protocol glue.