Reaper Daemon MCP Server

<p align="center"> <img src="docs/assets/readme-header.png" alt="Reaper Daemon. Nothing is listening." width="100%"> </p>

Reaper Daemon

Reaper Daemon is a REAPER MCP server and file bridge for driving REAPER from an AI agent, including mixing your session with Claude or any other agent. No network socket, no port, no extensions.

The agent drops a JSON command file in a folder. A Lua script inside REAPER runs it and writes a JSON result back. That's the whole protocol. It works with Claude Code, Codex, Cursor, or anything else that can read and write files, and an optional stdio MCP server, reaper_mcp.py, exposes the same bridge as tools for Claude Desktop and any other MCP client.

macOS, Windows, Linux. Pure Lua inside REAPER, plain Python 3 outside, no pip packages for the core bridge and MCP server. Audio-to-drum MIDI transcription uses a separate optional model environment. Every change runs inside a REAPER undo block, so Ctrl+Z reverts anything an agent does.

Install

git clone https://github.com/wretcher207/reaper-daemon.git
cd reaper-daemon
python3 setup/install.py

Restart REAPER, then check the bridge is alive:

python3 reaperd.py status

Prefer ReaPack, or want to load the bridge by hand? See docs/install.md.

Claude plugin

The repository is also a Claude plugin. It bundles the MCP server with four skills: drum programming, drum humanizing, guitar and bass parts, and MIDI for an existing arrangement. The plugin drives the install above, so clone and run the installer first.

When you add the plugin, Claude asks for two settings:

• Reaper Daemon folder: where you cloned it. Default ~/reaper-daemon.
• Python command: default python3. On Windows, use python or py if python3 isn't on your PATH.

Cowork doesn't ask, so it uses those defaults. To try the plugin in Claude Code straight from your clone:

claude --plugin-dir /path/to/reaper-daemon

The MCP server runs on your computer, next to REAPER. It works in Claude Code and in Cowork sessions on your machine. Chat on claude.ai loads the skills but can't reach REAPER.

Mix with an AI agent

Point Claude, or any agent talking to Reaper Daemon, at your open REAPER session and ask it to work on the mix. It reads every plugin and parameter with scan_fx, sets FX values in real units like "-2.5 dB", and writes automation. verify_change captures the track before and after a move and reports what changed in the audio, so you are not taking its word for it. Every move sits inside a REAPER undo block, and your ears make the call.

Example prompts:

• "The bass is muddy around 300 Hz, pull it down."
• "Bring the vocal down so it sits with the mix instead of on top."
• "Tune the bass until its LUFS is down 3 dB."
• "What plugins are on the drum bus, and what are they set to?"

See MCP server for setup and Verify for what the measurements do and do not prove.

What it does

Area	Commands
Project	transport, tempo, cursor, time selection, render, save
Tracks	add, delete, rename, select, volume, pan, mute, solo, arm, color
Routing	read sends and receives, create sends, toggle master feed
FX	add, remove, bypass, reorder, set parameters, write automation, save chains
Markers, regions, media items	full read and write
MIDI	insert MIDI files, plus a drum DSL with humanization
Transcription	turn an audio item into drum MIDI with an optional local analysis runtime
Guitar and bass	shred renders a humanized riff, band cuts a whole rhythm section
Discovery	scan_fx dumps every plugin and parameter; discover_drum_map reads any kit's note map
Verify	measure loudness, spectrum and dynamics before and after a mix move

The bridge knows nothing about any specific plugin or drum library. Agents discover what a project contains and act on it by name.

Three ways to talk to it

CLI. One Python entry point for everything an agent does.

python3 reaperd.py send commands/examples/get_context.json --wait
python3 reaperd.py shred --track argent-l --bars-file riff.txt --seed 101

MCP server. reaper_mcp.py wraps the bridge as tools over stdio. Ask Claude Desktop to "measure the drums" and it does.

Daemon Console. A chat panel docked inside REAPER, backed by a headless Claude Code session that always knows which track you have selected.

Docs

Install	one-line installer, ReaPack, manual load
CLI	reaperd.py reference
MCP server	setup for Claude Desktop and other clients
Daemon Console	the in-REAPER chat panel
Drums	kit discovery, stem profiling, humanize
Drum workshop	separate composition briefs, MIDI comparisons, scoped audition feedback
Drum transcription	audio to MIDI, background jobs, kit mapping
Guitar and bass	shred and band
Mix recipes	capture, compare and rebuild a mix setup
Verify	closed-loop mix moves with measured proof
Protocol	the file wire format
Troubleshooting	silent captures, stale heartbeats
Security	trust model and the optional token
Develop	tests, CI, repo layout

Agents should read AGENTS.md, CLAUDE.md, and bridge/command_schema.md. Two bundled skills, arrangement-midi and drum-humanize, cover MIDI composition and drum humanization.

Security

Any process that can write to inbox/ can drive REAPER. Keep the bridge folder local and off shared drives. Details in docs/security.md.

What it runs and sends

Everything runs on your machine. The MCP server and CLI are plain Python with no network calls. The bridge is a Lua script inside REAPER. It trades JSON files with the server through the Reaper Daemon folder, which also holds logs and the MIDI files it generates. Renders and captures write audio files only if you turn on audio writes, which are off by default. Nothing leaves your computer.

Three optional pieces do more, and only if you install them:

• Drum transcription downloads its Python packages and model weights during setup, and Demucs downloads its weights on the first separation job. Audio stays local.
• analyze_track and compare_tracks run Post Mortem from your PATH.
• The Daemon Console starts a Claude Code session on your machine, which talks to Anthropic like any Claude Code session.

License

MIT. See LICENSE.

Keyboard performance setup, MIDI/controller tests and template saving are documented in the performance workflow.