MCP GitHub Code Reviewer

An MCP (Model Context Protocol) server that gives Claude the ability to fetch Pull Request diffs from GitHub and post inline code review comments directly on the PR — either as a pending draft for you to approve, or published immediately.

How it works

You (Claude Code) ──► MCP Server (src/index.ts) ──► GitHub API
                           │
                     Two tools + two prompts exposed:
                     • get_pull_request_diff
                     • post_pr_review_comment
                     • review_pr (prompt — guided)
                     • review_pr_auto (prompt — autonomous)

When running as an MCP server, Claude can call these tools in response to natural language prompts. You describe which PR to review, and Claude fetches the diff, analyzes the code, and posts structured inline comments.

You can also use the built-in review_pr prompt to give Claude step-by-step instructions automatically — no need to describe the process manually each time.

Related MCP server: PR Review MCP Server

Prompts available

There are two prompts, each with a different review style:

review_pr — guided review

Instructs Claude to follow a fixed step-by-step process: fetch the diff, analyze it across specific categories, and post inline comments.

The prompt instructs Claude to focus on:

• Bugs and logic errors

• Security vulnerabilities

• Performance issues

• Code style and readability

• Missing error handling

review_pr_auto — autonomous review

Just fetches the diff and lets the LLM review freely using its own judgment — no rigid checklist.

Tools available

get_pull_request_diff

Fetches the raw diff of a Pull Request from GitHub.

post_pr_review_comment

Posts an inline review comment on a specific line of a changed file.

Prerequisites

• Node.js 18+

• A GitHub Personal Access Token with repo scope

• Claude Code (to use as an MCP server)

Installation

npm install

Configuration

Create a .env file in the project root:

GITHUB_TOKEN=ghp_YourGitHubTokenHere

Running as an MCP server (Claude Code)

Add this server to your Claude Code MCP configuration (~/.claude/claude_desktop_config.json or via claude mcp add):

{
  "mcpServers": {
    "github-code-reviewer": {
      "command": "npx",
      "args": ["tsx", "/path/to/mcp-github-reviewer/src/index.ts"],
      "env": {
        "GITHUB_TOKEN": "ghp_YourGitHubTokenHere"
      }
    }
  }
}

Or start the server manually:

npx -y @modelcontextprotocol/inspector@latest --mode cli npx tsx src/index.ts

Example usage

Guided review (step-by-step):

Use the prompt review_pr with owner="seu-usuario", repo="seu-repo", pull_number=42

Autonomous review (LLM decides):

Use the prompt review_pr_auto with owner="seu-usuario", repo="seu-repo", pull_number=42

Publish comments immediately:

Use the prompt review_pr with owner="seu-usuario", repo="seu-repo", pull_number=42, status="PUBLIC"

Manual prompt (without using any built-in prompt):

Review the PR 360 in seu-usuario/seu-repositorio and use post_pr_review_comment with status: "PENDING" so I can double-check everything on GitHub before publishing.

Project structure

mcp-github-reviewer/
├── src/
│   └── index.ts      # MCP server — exposes tools to Claude
├── package.json
├── tsconfig.json
└── .env              # GITHUB_TOKEN goes here

Dependencies