feat(git): add git worktree tools (list, add, remove)

[karawitan]

Description

Add three new tools to mcp-server-git for managing git worktrees:

• git_worktree_list — List all worktrees of a repository
• git_worktree_add — Create a new worktree, optionally creating a new branch for it
• git_worktree_remove — Remove a worktree, with optional force flag for modified worktrees

Server Details

• Server: git (mcp-server-git)
• Changes to: tools

Motivation and Context

Git worktrees are a standard git feature for working on multiple branches simultaneously in separate directories without stashing. They are commonly used in parallel development workflows (e.g., working on a feature branch while keeping the main branch checked out for quick fixes).

The official mcp-server-git currently has no worktree support, forcing LLM agents to fall back to shell commands. Several third-party MCP git servers already implement worktree tools (e.g., mcp-server-git-rs, lileeei/mcp-git-tools, georgeasoto/worktree-tools-mcp), indicating clear demand. Adding this to the reference server provides a consistent, tested, and security-hardened implementation.

How Has This Been Tested?

• 8 new unit tests covering: list, add (with branch, with base branch, default branch), remove, force remove, and flag injection guards for both add and remove
• All 55 tests pass (8 new + 47 existing)
• pyright: 0 errors, 0 warnings
• ruff: All checks passed

Breaking Changes

None. This is purely additive — three new tools are registered alongside the existing 12.

Types of changes

• New feature (non-breaking change which adds functionality)

Checklist

• I have read the MCP Protocol Documentation
• My changes follows MCP security best practices
• I have updated the server's README accordingly
• I have tested this with an LLM client
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have documented all environment variables and configuration options

Additional context

Security

Each new tool includes defense-in-depth guards rejecting arguments starting with - to prevent flag injection, matching the established pattern in existing tools (git_diff, git_checkout, git_show, git_create_branch, git_log, git_branch). The git_worktree_remove tool is annotated with destructiveHint=true since it deletes a working directory.

Implementation

GitPython does not provide a high-level worktree API (it only has a WorkTreeRepositoryUnsupported exception). The implementation uses GitPython's low-level repo.git.worktree command interface, which wraps the git worktree subcommand directly. This is the same approach the existing git_branch tool uses (repo.git.branch(...)).

Tool annotations

Tool	readOnly	destructive	idempotent
git_worktree_list	true	false	true
git_worktree_add	false	false	false
git_worktree_remove	false	true	false