The value is not in the five tools, it is in who answers them: a model you chose and pay for, sitting outside the assistant that wrote the code. Five prompts wrapped as tools is a thin layer, and thin is the right shape here — the whole thing is short enough to read before you let it near a diff.
A single Ruby file on the fast-mcp framework, run over stdio, that offers five differently framed requests to a model you choose on OpenRouter. Because the model is yours to pick, the reviewer can be a different model from the assistant that wrote the code — which is the entire point of a second opinion.
- A general code review returning actionable feedback
- A performance pass looking specifically for bottlenecks and optimisations
- A security pass looking for vulnerabilities in code you point it at
- A brainstorming tool for ideation and solution exploration
- An open collaboration tool for working a problem through step by step
- Your choice of model behind all five — Gemini by default, with OpenAI, Grok, DeepSeek and Claude models listed as alternatives
Ruby 3.0 or newer and an OpenRouter API key in the environment; the calls are billed to your OpenRouter account. Gems install themselves through inline bundler on first launch, and that first launch is where people get stuck — the install can outlast a client's startup timeout, so run the server once from a terminal before wiring it into a client, or raise the client's timeout. It logs to standard error for the host to capture.