Patch File MCP

What is Patch File MCP?

Patch File MCP is an MCP server that enables AI agents (like Claude) to make precise changes to files in projects using a block-based patch format. It provides a single tool for applying targeted edits without rewriting entire files, with built-in safety through exact text matching and uniqueness verification.

How to use Patch File MCP?

Install with uvx or from source, then configure your MCP client (e.g., Claude Desktop) by adding a "patch-file" entry in the mcpServers JSON config with the command and --allowed-dir arguments. The server starts automatically when the client uses it; no manual launch is needed. Use the patch_file tool with a file path and patch content formatted in SEARCH/REPLACE blocks.

Key features of Patch File MCP

• Applies multiple search-replace blocks in a single request.
• Verifies each search text appears exactly once in the file.
• Restricts file operations to allowed directories only.
• Provides clear error messages when a patch cannot be applied.
• Designed as a safer alternative to edit_block from desktop-commander.

Use cases of Patch File MCP

• An AI agent refactoring a function inside a source code file without touching other parts.
• Applying a series of configuration changes to a project file in one chat turn.
• Fixing a bug by replacing specific lines inside a large log or data file.
• Updating documentation snippets across multiple files in a codebase.

FAQ from Patch File MCP

How does Patch File MCP differ from the edit_block tool?

Patch File MCP supports multiple blocks in one operation, offers stronger safety checks (exact match, uniqueness), and gives more detailed error feedback, making it a better choice for most file editing tasks.

What are the runtime requirements?

Python 3.11 or higher, the fastmcp package (version >=2.2.0, <3.0.0), and optionally uvx from the uv Python package manager for the no-install method.

Which directories can the server access?

Access is limited to directories specified via the --allowed-dir argument (can be used multiple times). Subdirectories are also allowed. If no directory is specified, only the user's home directory is accessible.

What happens if a search block doesn't match or matches multiple times?

The tool returns an error. Each search text must appear exactly once in the file for the patch to be applied; otherwise, no changes are made and a descriptive error is reported.