pairLABSCO SUMMARY
The reviewer is a different model from the author.
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.
What it is
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.
What you get
- 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
Requirements
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.
Setup effort
Build from source — git clone https://github.com/K4sku/ai-pair-programmer-mcp.git
USE CASES
01
Getting a second model's read on your code
Paste the code and ask for review, and the feedback comes back from a different model than the one that produced it — the disagreements are the part worth reading.
02
Checking a hot path before optimising by guess
The performance tool looks specifically for bottlenecks and suggests optimisations, which is a different prompt from a general review and returns different findings.
03
A security pass on code that touches auth
Point it at authentication, session or input-handling code for a vulnerability-focused review, separately from whatever a general review turned up.
04
Thinking a problem through before writing anything
Use the collaboration tool to work through an algorithm step by step, or the brainstorming tool when the need is options rather than an answer.
5 tools
Listed in project docs. Your client may show a different list.
reviewbrainstormreview_performancereview_securityBEFORE YOU INSTALL
What to know first
Tools you get
5 tools named in the project's documentation.
Requires
- Ruby 3.0+
- OPENROUTER_API_KEY in your environment
Where it runs
The documented client runs the server on your machine.
INSTALLATION
Connect your client
You clone this one yourself.
Server setup
TERMINAL
git clone https://github.com/K4sku/ai-pair-programmer-mcp.git
cd ai-pair-programmer-mcp
export OPENROUTER_API_KEY="<YOUR_OPENROUTER_API_KEY>"
ruby ./server.rbMCP Clients
Claude Desktop
CLAUDE DESKTOP · JSON
{
"mcpServers": {
"AiPairProgrammer": {
"command": "ruby",
"args": [
"<YOUR_PATH_TO_SERVER>"
],
"env": {
"OPENROUTER_API_KEY": "<YOUR_OPENROUTER_API_KEY>"
}
}
}
}
