MCP Tools

Enables agents to quickly find and edit code in a codebase with surgical precision. Find symbols, edit them everywhere.

📋 Table of Contents

• 🚀 Quick Start
• 🛠️ Available Tools
• ⚡ Surgical Code Editing: Surgical Precision
• 🎛️ Environment Variables
• 🖥️ Server Usage
• 💻 CLI Usage
• 🏗️ Architecture
• 🧪 Development
• 🛠️ Troubleshooting
• 📝 License
• 🔗 Links

🚀 Quick Start

Option 1: NPX (Recommended)

Add this to ~/.cursor/mcp.json for Cursor, ~/.config/claude_desktop_config.json for Claude Desktop.

{
  "mcpServers": {
    "mcp-files": {
      "command": "npx",
      "args": ["-y", "mcp-files"]
    }
  }
}

Option 2: Docker

{
  "mcpServers": {
    "mcp-files": {
      "command": "docker",
      "args": [
        "run",
        "--rm",
        "-i",
        "flesler/mcp-files"
      ]
    }
  }
}

Option 3: HTTP transport

First run the server:

TRANSPORT=http PORT=3000 npx mcp-files

Then:

{
  "mcpServers": {
    "mcp-files": {
      "type": "streamableHttp",
      "url": "http://localhost:3000/mcp"
    }
  }
}

🛠️ Available Tools

Tool	Description	Parameters
read_symbol	Find and extract code blocks by symbol name(s) from files. Supports multiple symbols via array	symbols (string[]), file_paths[]?, limit?, optimize?
import_symbol	Import and inspect JavaScript/TypeScript modules and their properties	module_path, property?
search_replace	Search and replace with intelligent whitespace handling and automation-friendly multiple match resolution	file_path, old_string, new_string, allow_multiple_matches?
insert_text	Insert/replace text at precise line ranges. Perfect for direct line operations from code citations (12:15:file.ts) and surgical edits in large files	file_path, from_line, text, to_line
os_notification	Send OS notifications using native notification systems	message, title?

⚡ Surgical Code Editing: Surgical Precision

The combination of read_symbol + insert_text unlocks revolutionary code editing capabilities that transform how AI agents work with codebases.

🎯 The Power Combo

1. Symbol Discovery (read_symbol) - Find ANY symbol(s) ANYWHERE in your codebase:

// Find single function/class/interface anywhere in repo
read_symbol({symbols: ["generateApiKey"]})
// → Returns: exact location (lines 45-52 in src/auth/tokens.ts)

// Find multiple symbols at once
read_symbol({symbols: ["User", "UserService", "UserInterface"]})
// → Returns: all matching symbols with their locations

// Optimize code for AI context (strips comments, normalizes indentation)
read_symbol({symbols: ["complexFunction"], optimize: true})
// → Returns: clean, tab-indented code without comments for AI processing

2. Surgical Editing (insert_text) - Make precise modifications using exact line ranges:

// Replace specific lines with surgical precision
insert_text(file: "src/auth/tokens.ts", from_line: 45, to_line: 52, text: "improved implementation")

// Insert new code without disruption
insert_text(file: "src/auth/tokens.ts", from_line: 45, text: "// Added security enhancement")

🚀 Superpowers Unlocked

🔍 Cross-Codebase Intelligence

• Find any symbol across entire repositories instantly
• No manual searching through files and folders
• Perfect accuracy even in massive codebases

✂️ Precision Surgery

• Edit exact functions, classes, or code blocks
• Replace implementations without affecting surrounding code
• Insert enhancements at perfect locations

🎛️ Zero-Error Refactoring

• Update function signatures everywhere they exist
• Modify APIs across all files simultaneously
• Fix bugs with surgical precision across entire codebase

💡 Real-World Magic

# Find and enhance any function
read_symbol("validateEmail") → lines 23-35 in utils/validation.ts
insert_text(from_line: 23, to_line: 35, text: "enhanced validation with regex")

# Add documentation to any symbol
read_symbol("processPayment") → line 87 in payment/processor.ts
insert_text(from_line: 87, text: "/** Secure payment processing with fraud detection */")

# Fix bugs anywhere in codebase
read_symbol("parseUserInput") → lines 156-162 in input/parser.ts
insert_text(from_line: 156, to_line: 162, text: "sanitized parsing logic")

This transforms AI from "helpful assistant" to "surgical code surgeon" 🦾

🎛️ Environment Variables

Variable	Default	Description
TRANSPORT	stdio	Transport mode: stdio or http
PORT	4657	HTTP server port (when TRANSPORT=http)
DEBUG	false	Enable debug mode and utils_debug tool

🖥️ Server Usage

You can either install and use mcp-files or npx mcp-files.

# Show help
mcp-files --help

# Default: stdio transport
mcp-files

# HTTP transport
TRANSPORT=http mcp-files
TRANSPORT=http PORT=8080 mcp-files

# With debug mode
DEBUG=true mcp-files

💻 CLI Usage

All tools can be used directly from the command line:

# Find single symbol in code (specific file)
mcp-files read_symbol "MyInterface" src/types.ts

# Find multiple symbols at once (comma-separated)
mcp-files read_symbol "User,UserService,UserInterface" src/

# Find symbol in current directory (default)
mcp-files read_symbol "MyInterface"

# Use wildcards for pattern matching
mcp-files read_symbol "get*,User*" src/

# Inspect imports
mcp-files import_symbol lodash get

# Replace text with smart whitespace handling
mcp-files replace_text config.json "old_value" "new_value"

# Send notifications
mcp-files os_notification "Task completed"

🏗️ Architecture

• Type-safe tools with Zod validation
• Self-contained modules in src/tools/
• Cross-platform support (Linux, macOS, Windows, WSL)
• Performance optimized with memoization
• Clear error handling with descriptive messages

🧪 Development

# Install dependencies
npm install

# Build
npm run build

# Development mode
npm run dev

# Lint
npm run lint:full

# Test
npm run ts test/index.test.ts

# CLI testing
node dist/index.js read_symbol "functionName" file.ts

# Multiple symbols (comma-separated in CLI)
node dist/index.js read_symbol "func1,func2,Class*" file.ts

# Or search current directory
node dist/index.js read_symbol "functionName"

🧹 Code Optimization

The read_symbol tool includes an optimize parameter that cleans up code for AI processing:

What it does:

• Strips comments: Removes //, /* */, and /** */ comments
• Collapses newlines: Multiple consecutive newlines become single newlines
• Normalizes indentation: Converts spaces to tabs (detects indentation token size automatically)
• Removes base indentation: Eliminates common leading whitespace

Usage:

// MCP mode - explicit control
read_symbol({symbols: ["MyClass"], optimize: true})  // optimized
read_symbol({symbols: ["MyClass"], optimize: false}) // raw code (default)

// CLI mode - always optimized
mcp-files read_symbol "MyClass" src/

Perfect for: Reducing token count in AI context windows while preserving code structure and readability.

🛠️ Troubleshooting

Requirements

• Node.js ≥20 - This package requires Node.js version 20 or higher

Common Issues

ERR_MODULE_NOT_FOUND when running npx mcp-files

• Problem: Error like Cannot find module '@modelcontextprotocol/sdk/dist/esm/server/index.js' when running npx mcp-files
• Cause: Corrupt or incomplete npx cache preventing proper dependency resolution
• Solution: Clear the npx cache and try again:

  npx clear-npx-cache
  npx mcp-files

• Note: This issue can occur on both Node.js v20 and v22, and the cache clear resolves it

Tools not showing up in MCP client:

• Verify Node.js version is 20 or higher
• Try restarting your MCP client after configuration changes

File operations failing:

• Ensure proper file permissions for the files you're trying to read/modify
• Use absolute paths when possible for better reliability
• Check that the target files exist and are accessible

📝 License

MIT - see LICENSE file.

🔗 Links

• 📦 NPM Package
• 🐙 GitHub Repository
• 🐛 Report Issues
• 📚 MCP Specification

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Built for AI agents 🤖