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 exposed:
                     • get_pull_request_diff
                     • post_pr_review_comment

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.

Tools available

get_pull_request_diff

Fetches the raw diff of a Pull Request from GitHub.

Parameter	Type	Description
owner	string	GitHub username or organization
repo	string	Repository name
pull_number	number	PR number

post_pr_review_comment

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

Parameter	Type	Description
owner	string	GitHub username or organization
repo	string	Repository name
pull_number	number	PR number
path	string	File path (e.g. src/app.js)
line	number	Line number where the comment will appear
body	string	Comment text in Markdown
status	string	PENDING saves as a draft (you publish on GitHub); PUBLIC submits immediately

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:

npm start

Example prompts

Use these prompts in Claude Code after the MCP server is connected:

---

Review with pending draft (recommended for first use):

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.

Claude will fetch the diff, analyze the code, and save the comments as a pending draft review on GitHub. You then go to the PR on GitHub and click "Submit review" when you're happy with the comments.

---

Review and publish immediately:

For immediate launch: "Review the PR and use post_pr_review_comment with status: "PUBLIC" to submit the comments directly."

Claude will post every comment live on the PR as soon as it finishes the analysis.

---

Full review in Portuguese:

Por favor, liste as alterações e faça o code review do PR número 42 do repositório seu-usuario/seu-repositorio. Se encontrar problemas, use a ferramenta de comentário para postar direto no GitHub.

Claude will list the changed files, analyze the diff, and post inline comments directly to the PR.

---

Project structure

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

Dependencies

Package	Role
@modelcontextprotocol/sdk	MCP server framework
@octokit/rest	GitHub API client
dotenv	Loads .env variables
tsx	Runs TypeScript directly without a build step