git-context-mcp: Instructions file for Claude Code

git-context-mcp

An MCP server that answers the question every developer asks: "why does this code exist?"

What this project does

TypeScript MCP server built with @modelcontextprotocol/sdk. It exposes 5 tools that combine local git operations (git blame, git log, git show) with GitHub API calls via the gh CLI to surface the full story behind any piece of code — the commit, the PR, and the original issue.

Project structure

src/index.ts      — entire server: helpers, tool handlers, server setup
dist/             — compiled output (gitignored)

Tools exposed

Tool	Purpose
blame_context	File + line range → who wrote it + PR + linked issues
commit_story	Commit hash → full narrative (message, PR, issues)
file_history	File → last N commits, each with PR context
search_commits	Keyword → matching commits + PR/issue context
file_contributors	File → ranked author table (commits, lines owned, date range)

Key implementation details

• All git operations use execSync with stdio: pipe so errors return "" instead of throwing
• GitHub API calls shell to gh api — no token needed beyond gh auth login
• findPRForCommit uses the GitHub commits→pulls endpoint (/repos/:owner/:repo/commits/:hash/pulls)
• Issue refs are extracted from PR bodies via #NNN and /issues/NNN patterns
• blame_context uses git blame -p (porcelain) and parses the structured block format

Dev commands

npm run build   # tsc compile to dist/
npm run dev     # tsc --watch
npm start       # run the compiled server

Testing with Claude Code

Add to ~/.claude/claude_mcp_config.json:

{
  "mcpServers": {
    "git-context": {
      "command": "node",
      "args": ["<absolute-path>/dist/index.js"]
    }
  }
}

Then in any repo ask Claude: "Why does line 42 of src/auth.ts exist?"