MCP PR Reviewer

Intelligent PR reviews powered by the Model Context Protocol and LLMs.

MCP PR Reviewer analyzes GitHub Pull Requests using AI, leveraging the Model Context Protocol for secure GitHub integration and providing detailed feedback.

🚀 Features

• MCP GitHub Integration: Securely fetches PR data using @modelcontextprotocol/server-github.
• AI-Powered Analysis: Uses configurable LLMs via OpenRouter for insightful code review.
• Structured Feedback: Provides a clear decision (Approve/Reject), summary, and key points.
• CLI & Server Modes: Usable both directly for analysis and as a server for integrations.
• Customizable: Choose your preferred LLM model.

🔧 Installation

# Install globally
npm install -g mcp-pr-reviewer

# Or use with npx without installing
npx mcp-pr-reviewer --help

💻 Usage

Prerequisites

Set the following environment variables:

• GITHUB_TOKEN: Your GitHub Personal Access Token with repo scope.
• OPENROUTER_API_KEY: Your API key from OpenRouter.ai.

Analyze a Pull Request

# Format
mcp-pr-reviewer analyze <owner> <repo> <pr-number> [options]

# Example
mcp-pr-reviewer analyze octocat hello-world 123

# Example with specific ports and model
mcp-pr-reviewer analyze myorg my-repo 456 --mcp-port 8081 --llm-port 8091 --model openrouter/anthropic/claude-3-haiku

Options:

• --mcp-port <port>: Port for the internal MCP GitHub server (default: 8080).
• --llm-port <port>: Port for the internal LLM provider server (default: 8090).
• -m, --model <model>: Specify the OpenRouter model ID (default: openrouter/optimus-alpha).

Run as a Server (for Integrations)

The server command starts only the LLM provider component, making it available as an MCP server for other tools or integrations (like GitHub Actions).

# Start the LLM Provider server
mcp-pr-reviewer server --port 8012 --model openrouter/google/gemini-pro

This allows external systems to call its analyze_pr capability.

🧩 MCP Configuration (Example for Cursor)

You can integrate mcp-pr-reviewer with tools like Cursor using an mcp.json file. Here's an example configuration:

{
  "mcpServers": {
    "GitHub MCP": {
      "command": "npx",
      "type": "stdio",
      "env": {
        "GITHUB_PERSONAL_ACCESS_TOKEN": "YOUR_GITHUB_PAT_HERE"
      },
      "args": [
        "@modelcontextprotocol/server-github"
      ]
    },
    "PR Reviewer": {
      "command": "npx",
      "type": "http",
      "baseUrl": "http://localhost:8012",
      "env": {
        "OPENROUTER_API_KEY": "YOUR_OPENROUTER_KEY_HERE"
      },
      "args": [
        "mcp-pr-reviewer",
        "server",
        "--port",
        "8012"
      ]
    }
  }
}

Note: Replace placeholders like YOUR_GITHUB_PAT_HERE and YOUR_OPENROUTER_KEY_HERE with your actual credentials.

🏗️ Architecture

The analyze command orchestrates two main components:

1. MCP GitHub Server: An instance of @modelcontextprotocol/server-github started internally to handle secure communication with the GitHub API.
2. LLM Provider Server: A simple Express server (lib/mcp-llm-provider.js) started internally that:
   • Accepts analysis requests.
   • Communicates with the OpenRouter API to get the LLM analysis.

The lib/analyze-pr.js script coordinates the process:

1. Connects to the running MCP GitHub Server (via HTTP) to fetch the PR diff.
2. Sends the diff to the running LLM Provider Server (via HTTP) for analysis.
3. Outputs the formatted review.

The server command only starts the LLM Provider Server, exposing it for external MCP calls.

🤝 Contributing

Contributions are welcome! Please fork the repository and submit a Pull Request.

1. Fork the repository
2. Create your feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add some amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

📜 License

MIT License - see the LICENSE file for details.

📚 FAQ

Q: What is Model Context Protocol (MCP)? A: An open standard allowing AI models to securely interact with tools and data sources. See modelcontext.dev.

Q: Does it work with private repositories? A: Yes, ensure your GITHUB_TOKEN has the necessary permissions (e.g., repo scope).

Q: Can I use models other than OpenRouter? A: Currently, it's hardcoded for OpenRouter. Modifying lib/mcp-llm-provider.js would be required to support other providers.

Q: How is this different from GitHub Copilot's PR Summary? A: This tool provides a more opinionated review, including an Approve/Reject decision and specific feedback points based on a configurable prompt, rather than just a summary.