Reaper Dev MCP Server

MCP (Model Context Protocol) server providing reference documentation for REAPER development, ReaScript API, JSFX programming, and ReaWrap API.

Purpose

This server provides static reference documentation that serves as a lookup reference for factual information about REAPER development. It helps prevent "token burn" by avoiding the need to rediscover common patterns and pitfalls in every session.

Features

• Queryable API Documentation: Use tools to search and get detailed function information
• JSFX Fundamentals: Core concepts and gotchas
• ReaScript API: Complete function reference with signatures and parameters (2,282 functions across C, EEL2, Lua, Python)
• ReaWrap API: Object-oriented wrapper documentation (14 classes, 736 methods)

Installation

Quick Start

Choose your IDE and follow the instructions:

• Claude Code CLI - Recommended, easiest setup
• Cursor IDE - Works with stdio or HTTP
• Claude Desktop - Requires HTTP server

Claude Code CLI

Prerequisites: Node.js v18+

Installation (one command):

claude mcp add --transport stdio --scope user reaper-dev -- npx -y reaper-dev-mcp

Verify it's working:

claude mcp list

You should see: reaper-dev: npx -y reaper-dev-mcp - ✓ Connected

That's it! The server will automatically start when Claude Code needs it. Restart your Claude Code session to use the tools.

Cursor IDE

Cursor supports both stdio and HTTP transports. Stdio is recommended (no background process needed).

Option A: stdio Transport (Recommended)

Prerequisites: Node.js v18+

1. Open Cursor settings:

   • macOS/Linux: ~/.cursor/mcp.json
   • Windows: %APPDATA%\Cursor\mcp.json

2. Add this configuration:

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

3. Restart Cursor

That's it! Cursor will spawn the server automatically when needed.

Option B: HTTP/SSE Transport

If you prefer HTTP (or stdio doesn't work), use this method:

1. Start the server in a terminal (keep it running):

   npx -y reaper-dev-mcp

   The server will start on http://localhost:3000. For a custom port:

   PORT=8080 npx -y reaper-dev-mcp

2. Open Cursor settings and add:

{
  "mcpServers": {
    "reaper-dev": {
      "type": "sse",
      "url": "http://localhost:3000"
    }
  }
}

3. Restart Cursor

Note: The server must be running before Cursor starts.

Claude Desktop

Claude Desktop requires HTTP/SSE transport.

Prerequisites: Node.js v18+

1. Start the server in a terminal (keep it running):

   npx -y reaper-dev-mcp

   The server will start on http://localhost:3000. For a custom port:

   PORT=8080 npx -y reaper-dev-mcp

2. Configure Claude Desktop:

   Locate your config file:

   • macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
   • Windows: %APPDATA%\Claude\claude_desktop_config.json
   • Linux: ~/.config/Claude/claude_desktop_config.json

3. Add this configuration:

{
  "mcpServers": {
    "reaper-dev": {
      "type": "sse",
      "url": "http://localhost:3000"
    }
  }
}

4. Restart Claude Desktop

Note: The server must be running before Claude Desktop starts.

Development Setup

If you want to modify the server or contribute:

git clone https://github.com/Conceptual-Machines/reaper-dev-mcp.git
cd reaper-dev-mcp
npm install
npm run build

Run in development mode:

npm run dev

Run tests:

npm run test

MCP Tools

get_function_info

Get detailed information about a function from JSFX, ReaScript, or ReaWrap API.

Parameters:

• api (string): One of "jsfx", "reascript", "reawrap"
• function_name (string): Name of the function to look up
• class_name (string, optional): Required for ReaWrap API queries

Examples:

// JSFX
{
  "api": "jsfx",
  "function_name": "sin"
}

// ReaScript
{
  "api": "reascript",
  "function_name": "TrackFX_GetParam"
}

// ReaWrap
{
  "api": "reawrap",
  "class_name": "track",
  "function_name": "add_fx_by_name"
}

search_functions

Search for functions across JSFX, ReaScript, or ReaWrap APIs.

Parameters:

• api (string): One of "jsfx", "reascript", "reawrap"
• query (string): Search query (function name, description, etc.)
• limit (number, optional): Maximum number of results (default: 10)

Examples:

{
  "api": "reawrap",
  "query": "create",
  "limit": 5
}

Resources

All documentation is available as MCP resources:

• reascript://jsfx-fundamentals - Core JSFX concepts
• reascript://parameter-system - REAPER parameter system
• reascript://parameter-modulation - Parameter linking (plink API)
• reascript://fx-containers - FX container system
• reascript://reawrap-api - ReaWrap API reference

API Coverage

The MCP server provides access to:

• JSFX API: 110 functions from official REAPER documentation
• ReaScript API: 2,282 functions organized by language (C, EEL2, Lua, Python)
• ReaWrap API: 14 classes with 736 methods

Success Criteria

✅ No More Token Burn: Stop rediscovering JSFX parameter indexing every session
✅ Fast Problem Solving: Quick lookup for plink API, container indices
✅ Prevent Regressions: Document all bugs so they're never repeated
✅ Reusable Knowledge: Can be used across all REAPER projects

License

MIT