In this article, Amanda goes through what a Ruby MCP server needs once it stops being a subprocess: Streamable HTTP instead of stdio, a choice between a standalone service and an endpoint inside an existing Rails app, statelessness so it survives more than one Puma worker, Host and Origin validation that a security advisory made mandatory, a shared token as the internal floor with OAuth as the answer beyond it, and read-only models and server_context deciding what any caller can actually reach.

Read more here: Running a Ruby MCP Server in Production