git MCP server

Instructions

Implementation Reference

• src/git/src/mcp_server_git/server.py:187-194 (handler)

  The main handler function that executes the git checkout by validating the branch name and calling repo.git.checkout.

  def git_checkout(repo: git.Repo, branch_name: str) -> str:
      # Defense in depth: reject branch names starting with '-' to prevent flag injection,
      # even if a malicious ref with that name exists (e.g. via filesystem manipulation)
      if branch_name.startswith("-"):
          raise BadName(f"Invalid branch name: '{branch_name}' - cannot start with '-'")
      repo.rev_parse(branch_name)  # Validates branch_name is a real git ref, throws BadName if not
      repo.git.checkout(branch_name)
      return f"Switched to branch '{branch_name}'"

• src/git/src/mcp_server_git/server.py:66-69 (schema)

  Pydantic BaseModel defining the input schema for the git_checkout tool: repo_path and branch_name.

  class GitCheckout(BaseModel):
      repo_path: str
      branch_name: str

• src/git/src/mcp_server_git/server.py:332-336 (registration)

  Registration of the 'git_checkout' tool in the list_tools() function using name=GitTools.CHECKOUT and the GitCheckout schema.

  Tool(
      name=GitTools.CHECKOUT,
      description="Switches branches",
      inputSchema=GitCheckout.model_json_schema(),
  ),

• src/git/src/mcp_server_git/server.py:105-105 (registration)

  Enum definition mapping GitTools.CHECKOUT to the tool name string 'git_checkout'.

  CHECKOUT = "git_checkout"

• src/git/src/mcp_server_git/server.py:464-469 (handler)

  Dispatch in call_tool() that invokes the git_checkout handler and returns the result as TextContent.

  case GitTools.CHECKOUT:
      result = git_checkout(repo, arguments["branch_name"])
      return [TextContent(
          type="text",
          text=result
      )]