Refactoring MCP Server

mcp-refactoring

An MCP (Model Context Protocol) server that exposes Martin Fowler's refactoring catalog to LLMs through a pluggable, language-agnostic architecture.

Features

• 71+ Refactorings: Full implementation of Martin Fowler's refactoring catalog
• Pluggable Architecture: Support for multiple languages (Python first, Ruby/Java/Go planned)
• Safe by Default: Preview mode shows changes before applying
• LLM-Optimized: TOON output format for token efficiency

Installation

# Using uvx (recommended)uvx mcp-refactoring
# Using pippip install mcp-refactoring
# Using pipxpipx install mcp-refactoring

Requirements

• Python 3.10+
• A language backend (e.g., molting-cli for Python)

Install the Python backend:

pip install molting-cli

Claude Desktop Configuration

Add to your Claude Desktop config:

{  "mcpServers": {    "refactoring": {      "command": "uvx",      "args": ["mcp-refactoring"]    }  }}

Available Tools

list_refactorings

List available refactorings with their parameter contracts.

list_refactorings(language="python", category="composing_methods")

preview_refactoring

Preview what changes a refactoring would make (dry-run).

preview_refactoring(    refactoring="extract-method",    target="src/order.py::Order::calculate#L10-L15",    params={"name": "calculate_tax"})

apply_refactoring

Apply a refactoring to the codebase.

apply_refactoring(    refactoring="rename-method",    target="src/order.py::Order::calc",    params={"new_name": "calculate_total"})

inspect_structure

Get structural information about code.

inspect_structure(path="src/order.py", depth="method")

analyze_code

Analyze code for smells and suggest refactorings.

analyze_code(path="src/order.py", smells=["long-method"])

Target Specification

Each language uses its native conventions:

Python

src/order.py::Order::calculate_total        # Methodsrc/order.py::Order::calculate_total#L10-L15  # Line rangesrc/order.py::Order                         # Class

Configuration

Create ~/.mcp-refactoring/config.toml:

[backends.python]enabled = truecommand = "molting"
[backends.ruby]enabled = falsecommand = "molting-rb"

Environment variable overrides:

MCP_REFACTORING_PYTHON_COMMAND=/path/to/moltingMCP_REFACTORING_PYTHON_ENABLED=true

Refactoring Categories

Based on Martin Fowler's catalog:

• Composing Methods: extract-method, inline-method, etc.
• Moving Features: move-method, extract-class, etc.
• Organizing Data: encapsulate-field, replace-type-code, etc.
• Simplifying Conditionals: decompose-conditional, guard-clauses, etc.
• Simplifying Method Calls: rename-method, add-parameter, etc.
• Dealing with Generalization: pull-up-method, extract-interface, etc.

Development

# Clone the repositorygit clone https://github.com/marshally/mcp-refactoring.gitcd mcp-refactoring
# Install in development modepip install -e ".[dev]"
# Run testspytest
# Run linterruff check .
# Run type checkermypy src/

License

MIT License - see LICENSE for details.