REAPER MCP

TwelveTake REAPER MCP

A TwelveTake Studios project.

[Setup guide, examples and FAQ -> twelvetake.com/tools/reaper-mcp](https://twelvetake.com/tools/reaper-mcp/)

Listed in the MCP Registry as mcp-name: com.twelvetake/reaper-mcp.

TwelveTake REAPER MCP is a Model Context Protocol server that enables AI assistants to control REAPER for mixing, mastering, MIDI composition and music production.

Version: 1.10.1

Why This Server

Workflow tools

In addition to direct control of REAPER, the server includes workflow tools that complete multi-step production tasks in a single call:

Zero Configuration

• File-based communication works immediately — no network setup, no ports to configure
• Stock REAPER only: the bridge is a plain Lua script and the analyzer is a JSFX plugin, so you don't install anything else in REAPER
• Copy the script, run it, connect your AI assistant

187 Tools Covering Real Production Needs

• Full FX control — add/remove plugins, get/set any parameter by index, manage presets, bypass
• FX parameter automation — automate any plugin knob (flanger depth, filter cutoff, etc.)
• Complete routing — sends, receives, sidechain routing to specific channel pairs
• Automation — create envelopes, add/edit points, set automation modes
• MIDI — create items, add notes individually or in batches, edit velocities
• MIDI editing — transpose, quantize with swing, humanize, snap to a scale, stretch, legato, strum, velocity ramps — each targetable by pitch range, beat window, or channel
• Audio items — import, split, duplicate, fade, position, mute
• Markers & regions: create, rename, delete and jump to them
• Session organizing: move tracks and folders, hide tracks from the arrange view or mixer, set track heights, rename takes and set the project playback rate
• Measurement: loudness, loudness range, true peak, the octave-band spectrum and stereo correlation for the master, a track or an item. It passes the EBU's synthetic compliance signals for loudness, true peak and loudness range.
• Undoable edits: every change the AI makes is one named step in REAPER's undo history ("MCP: delete track"), so Ctrl+Z in REAPER reverses one tool call at a time

Requirements

• REAPER (any recent version; full live suite green through REAPER 7.79)
• Python 3.10+ (for the MCP server)
• An MCP-compatible AI assistant

Installation

1. Install the Bridge Script in REAPER

The bridge is a Lua script that runs inside REAPER. The MCP server works on your project through it. Install it one of three ways.

Option A: one command, then run it once in REAPER

uvx twelvetake-reaper-mcp --install-bridge

That copies reaper_mcp_bridge.lua into REAPER's Scripts folder for your platform, and the TwelveTake MCP Analyzer, a JSFX plugin that the measurement tools use, into Effects/TwelveTake. If a different copy of the bridge is already there, it backs that copy up first. It writes nothing else, and the server never touches your REAPER installation on its own. Pass a path if REAPER is portable or installed somewhere unusual: --install-bridge "/path/to/REAPER/Scripts".

Then load it in REAPER. Open Actions → Show action list:

Click New action → Load ReaScript:

Select reaper_mcp_bridge.lua in the Scripts folder and click Open:

The script is now in the action list. Select it and click Run:

The bridge runs in the background, without opening a window, until you close REAPER. Step 3 checks that it is working.

Next time, find it by typing mcp bridge in the action list's filter box, or have REAPER start it for you (below).

Option B: ReaPack

If you use ReaPack, open Extensions → ReaPack → Import repositories:

and paste this address:

https://github.com/TwelveTake-Studios/reaper-mcp/raw/main/index.xml

Then open Extensions → ReaPack → Browse packages, find TwelveTake REAPER MCP bridge, right-click it, choose Install, and click OK:

ReaPack adds the script to the action list and installs the analyzer. Run the script from there as in option A.

Option C: by hand

1. Copy reaper_mcp_bridge.lua to your REAPER Scripts folder:

• Windows: %APPDATA%\REAPER\Scripts\
• macOS: ~/Library/Application Support/REAPER/Scripts/
• Linux: ~/.config/REAPER/Scripts/

1. Copy twelvetake_mcp_analyzer.jsfx to Effects/TwelveTake/, next to that Scripts folder. The measurement tools need it; nothing else does.
2. Load and run the script as in option A.

Start the bridge with REAPER

A script stops when REAPER closes. To have REAPER start the bridge every time it launches:

uvx twelvetake-reaper-mcp --install-bridge --autostart

That adds a marked block to __startup.lua in REAPER's Scripts folder, backing the file up first, and leaves anything else in it alone. --remove-autostart takes the block out again. If you installed with ReaPack, run uvx twelvetake-reaper-mcp --autostart instead; it points REAPER at the ReaPack copy.

Updating

From 1.7.8 on, an update needs no step inside REAPER:

uvx twelvetake-reaper-mcp@latest --install-bridge

The running bridge loads the new script by itself, and the command tells you so, for example:

The running bridge reloaded itself: 1.7.8 -> 1.7.9.

With ReaPack, Extensions → ReaPack → Synchronize packages fetches the new script. It runs the next time the bridge starts, or right away with uvx twelvetake-reaper-mcp --reload-bridge. The server also asks a running bridge to reload when the bridge is too old for it.

Updating from 1.7.7 or older needs one last manual step: run the script in REAPER again after installing it.

2. Install and Configure the MCP Server

The server is published on PyPI as `twelvetake-reaper-mcp`. The simplest path is to let your MCP client launch it with uvx (or pipx) — nothing to install by hand.

Add it to your MCP client's configuration (e.g. .mcp.json, or your client's MCP settings):

{

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

VS Code uses a top-level servers key with "type": "stdio" instead of mcpServers.

To confirm the server starts on its own:

uvx twelvetake-reaper-mcp

or: pipx run twelvetake-reaper-mcp

It waits quietly for a client to connect — press Ctrl+C to stop.

3. Verify

With REAPER open and the bridge running, ask your assistant "how many tracks are in my project?" — a number back means the server, bridge, and REAPER are all talking.

---

Run from source (for development)

To work on the server itself, run it from a clone instead of from PyPI. Install the dependencies:

pip install -r requirements.txt   # or: pip install "mcp>=1.2.0,<2.0"

Point your MCP client at the local script:

{

"mcpServers": { "reaper": { "command": "python", "args": ["path/to/reaper_mcp_server.py"] } } }

Then check the connection with:

python test_connection.py

Nix flake (optional)

If you use Nix, the repo ships a flake-based dev shell that provides Python 3.12 and creates/activates a virtualenv for you:

# Enter the dev shell manually

nix develop

Or, with direnv, auto-activate on cd:

direnv allow

Then install the dependencies as usual:

pip install -r requirements.txt

This pins the Python version and keeps dependencies isolated from your system.

Note: the x86_64-linux dev shell is tested and working. The macOS (Darwin) shells are

provided but have not been tested — confirmation from a macOS user is welcome.

How It Communicates

The server and the bridge exchange JSON files in a mailbox directory that the bridge script polls from inside REAPER. There is no network configuration and no port to open.

MCP Server                    REAPER Bridge

│ │ ├── writes request_N.json ────►│ │ ├── processes request │◄── reads response_N.json ────┤

Bridge directory: REAPER's own Scripts/mcp_bridge_data, resolved per platform:

Override with REAPER_BRIDGE_DIR for portable installs. The server prints the directory it resolved to stderr on startup, and includes it in any timeout error.

The HTTP transport that shipped alongside this was removed in v1.7.2. It had been deprecated since v1.2.1, and its request parser could never read a POST body, so no call it was handed ever reached REAPER. REAPER_COMM_MODE no longer does anything.

Quick Start Examples

Basic Track Operations

"How many tracks are in my project?"

"Create a new track called 'Vocals'" "Set track 0 volume to -6dB" "Mute track 2" "Solo the drums track"

Mixing

"Add ReaComp to the bass track"

"Set up sidechain compression from the kick to the bass" "Create a drum bus and route tracks 0-3 to it" "Add a mastering chain to the master track"

FX and Parameters

"What plugins are on track 0?"

"Get the parameters for the compressor on track 1" "Set the threshold to -20dB" "Bypass the EQ on the vocal track"

MIDI Composition

"Create a 4-bar MIDI item on track 0"

"Add a C major chord at the start" "Get all the notes in the MIDI item" "