RubyLLM 2.1: MCP, Judgments, Evaluations, and Less Work on Every Call

RubyLLM 2.1 is out. I released it on stage at Deccan Queen on Rails in Pune. It builds on 2.0 and adds an MCP client, typed judgments, evaluations, tool progress, OpenTelemetry tracing, and a nineteenth provider. It’s also faster, with no code changes. In this post: MCP client Judgments Evaluations Faster by default Tool progress OpenTelemetry Smaller changes Upgrading from 2.0 An MCP Client Where You Decide What the Model Sees In RubyLLM 2.1 an MCP server is a Ruby class you own: it lives in your repo, and it says exactly which tools the model gets. class Linear < RubyLLM::MCP url "https://mcp.linear.app/mcp" inputs :user oauth owner: :user only :list_issues, :get_issue, :create_issue # the model sees these three requires_approval :create_issue end chat = RubyLLM.chat.with_mcp(Linear.new(user: current_user)) # one connection per user chat.ask "What's blocking the release?" To try a server before shaping it, connect from the console. Every tool becomes a Ruby method: >> docs =…