git MCP server

Instructions

Implementation Reference

• src/git/src/mcp_server_git/server.py:119-126 (handler)

  Core handler function that computes the git diff against a specified target ref

  def git_diff(repo: git.Repo, target: str, context_lines: int = DEFAULT_CONTEXT_LINES) -> str:
      # Defense in depth: reject targets starting with '-' to prevent flag injection,
      # even if a malicious ref with that name exists (e.g. via filesystem manipulation)
      if target.startswith("-"):
          raise BadName(f"Invalid target: '{target}' - cannot start with '-'")
      repo.rev_parse(target)  # Validates target is a real git ref, throws BadName if not
      return repo.git.diff(f"--unified={context_lines}", target)

• src/git/src/mcp_server_git/server.py:33-36 (schema)

  Pydantic input schema for the git_diff tool

  class GitDiff(BaseModel):
      repo_path: str
      target: str
      context_lines: int = DEFAULT_CONTEXT_LINES

• src/git/src/mcp_server_git/server.py:302-306 (registration)

  Registration of the git_diff tool in the MCP server's list_tools method

  Tool(
      name=GitTools.DIFF,
      description="Shows differences between branches or commits",
      inputSchema=GitDiff.model_json_schema(),
  ),

• src/git/src/mcp_server_git/server.py:412-417 (handler)

  MCP call_tool dispatcher case that executes the git_diff tool and formats the response

  case GitTools.DIFF:
      diff = git_diff(repo, arguments["target"], arguments.get("context_lines", DEFAULT_CONTEXT_LINES))
      return [TextContent(
          type="text",
          text=f"Diff with {arguments['target']}:\n{diff}"
      )]