TwelveTake REAPER MCP

A TwelveTake Studios project.

A comprehensive Model Context Protocol (MCP) server that enables AI assistants to control REAPER DAW for mixing, mastering, MIDI composition, and full music production workflows.

Version: 1.6.0

Why This Server

Workflow Automation, Not Just API Wrappers

Most MCP servers just wrap REAPER's API and call it a day. This one includes production workflow helpers that handle multi-step operations in a single call:

Tool	What it does for you
setup_sidechain_compression()	Creates send, routes to channels 3-4, configures ReaComp's detector input — complete sidechain setup in one call
add_mastering_chain()	Adds ReaEQ → ReaComp → ReaEQ → ReaLimit to master track with proper signal flow
add_parallel_compression()	Creates a bus track, sets up the send, adds compressor — NY-style compression ready to blend
create_bus()	Creates a submix track and routes your specified tracks to it
get_project_summary()	Returns track count, all track names/volumes/pans/FX, markers, regions, tempo, time signature — everything your AI needs in one call

Zero Configuration

• File-based communication works immediately — no network setup, no ports to configure
• Stock REAPER Lua only — the bridge script has no dependencies, nothing extra to install in REAPER
• Copy the script, run it, connect your AI assistant

176 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, edit, navigate, render by region

Requirements

• REAPER (any recent version; full live suite green through REAPER 7.77)
• Python 3.8+ (for the MCP server)
• An MCP-compatible AI assistant

Installation

1. Install the Bridge Script in REAPER

The bridge script runs inside REAPER and handles communication with the MCP server.

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/
2. In REAPER: Actions → Show action list → Load ReaScript
3. Select reaper_mcp_bridge.lua and click Run

You should see "REAPER MCP Bridge (File-based, Full API) started" in REAPER's console.

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.

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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 httpx

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.

Communication Modes

The file-based bridge is the supported path — it is reliable and needs no extra setup. HTTP mode is deprecated (see below).

File-Based (Default, Recommended)

Uses JSON files for communication. More reliable, no network configuration needed. This is the only actively maintained path; all tools are guaranteed to work here.

MCP Server                    REAPER Bridge
    │                              │
    ├── writes request_N.json ────►│
    │                              ├── processes request
    │◄── reads response_N.json ────┤

Bridge directory: %APPDATA%\REAPER\Scripts\mcp_bridge_data

HTTP Mode (Deprecated)

Deprecated as of v1.2.1. The HTTP bridges (reaper_web_server.lua / reaper_web_server.py) are kept for existing users but are no longer maintained and will not receive new tools. They may be removed in a future major release (v2.0). Use the file bridge instead.

Uses HTTP requests on localhost. Requires additional setup:

• Lua HTTP bridge: Requires LuaSocket (install via ReaPack → "sockmonkey")
• Python HTTP bridge: Requires Python enabled in REAPER preferences

# Set environment variable to use HTTP mode
REAPER_COMM_MODE=http python reaper_mcp_server.py

Default port: 9000

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"
"Set the velocity of note 0 to 100"

Transport and Navigation

"Play the project"
"Stop playback"
"Set the cursor to 30 seconds"
"Add a marker called 'Chorus' at the current position"

Project Management

"What's the project tempo?"
"Set the tempo to 120 BPM"
"Save the project"
"Render to D:/Output/mix.wav"

Tool Reference

Track Operations (23 tools)

Tool	Description
get_track_count()	Get total number of tracks (excluding master)
get_track(index)	Get track info (name, volume, pan, mute, solo)
get_all_tracks()	Get info for all tracks
get_master_track()	Get master track info
insert_track(index, name)	Create a new track
delete_track(index)	Delete a track
set_track_name(index, name)	Rename a track
set_track_volume(index, db)	Set volume in dB
set_track_pan(index, pan)	Set pan (-1 to 1)
set_track_mute(index, mute)	Mute/unmute track
set_track_solo(index, solo)	Solo/unsolo track
set_track_phase(index, invert)	Invert phase
set_track_width(index, width)	Set stereo width (0-2)
set_track_color(index, r, g, b)	Set track color
get_track_peak(index, channel)	Get current peak level (dB)
get_track_peak_hold(index, channel)	Get held peak since last reset (dB)
clear_all_peak_indicators()	Reset peak hold on all tracks
get_track_master_send(index)	Get master/parent send state
set_track_master_send(index, enabled)	Enable/disable master send
set_track_as_folder(index, depth)	Set as folder parent/child
arm_track(index, arm)	Arm for recording
set_track_input(index, input)	Set record input
set_track_monitor(index, mode)	Set monitor mode

FX Operations (16 tools)

Tool	Description
track_fx_get_count(index)	Count FX on track
track_fx_get_list(index)	List all FX with details
track_fx_add_by_name(index, name, position?)	Add FX plugin (optionally at position)
track_fx_move(index, fx_index, new_position)	Reorder FX in the chain
track_fx_delete(index, fx_index)	Remove FX
track_fx_get_name(index, fx_index)	Get FX name
track_fx_get_enabled(index, fx_index)	Check if enabled
track_fx_set_enabled(index, fx_index, enabled)	Enable/bypass FX
track_fx_get_num_params(index, fx_index)	Count parameters
track_fx_get_param_name(index, fx_index, param)	Get parameter name
track_fx_get_param(index, fx_index, param)	Get parameter value
track_fx_set_param(index, fx_index, param, value)	Set parameter value
get_fx_presets(index, fx_index)	List available presets
get_fx_preset(index, fx_index)	Get current preset
set_fx_preset(index, fx_index, name)	Load preset
save_fx_preset(index, fx_index, name)	Save current settings as preset

ReaEQ Operations (5 tools)

Dedicated ReaEQ band control using REAPER's EQ-specific API, which handles ReaEQ's non-linear parameter curves (dB gain, log frequency, log Q) correctly.

Tool	Description
find_eq(track, instantiate?)	Find ReaEQ on a track (optionally add it)
get_eq_bands(track, fx)	Read all ReaEQ bands with human-readable values
set_eq_band(track, fx, bandtype, bandidx, paramtype, value, is_normalized?)	Set a band parameter (Hz, dB, or Q)
get_eq_band_enabled(track, fx, bandtype, bandidx?)	Check whether a band is enabled
set_eq_band_enabled(track, fx, bandtype, bandidx?, enabled?)	Enable/disable a band

Take FX Operations (11 tools)

Per-take (per-item) FX, mirroring the track FX tools. Every take is addressed by (track_index, item_index, take_index).

Tool	Description
take_fx_get_count(track, item, take)	Count FX on a take
take_fx_get_list(track, item, take)	List all take FX with details
take_fx_add_by_name(track, item, take, name)	Add FX plugin to a take
take_fx_delete(track, item, take, fx)	Remove FX from a take
take_fx_get_name(track, item, take, fx)	Get take FX name
take_fx_get_enabled(track, item, take, fx)	Check if enabled
take_fx_set_enabled(track, item, take, fx, enabled)	Enable/bypass take FX
take_fx_get_num_params(track, item, take, fx)	Count parameters
take_fx_get_param_name(track, item, take, fx, param)	Get parameter name
take_fx_get_param(track, item, take, fx, param)	Get parameter value
take_fx_set_param(track, item, take, fx, param, value)	Set parameter value

Take Management & Comping (7 tools)

Multi-take workflows: list/switch/delete takes, explode/crop, REAPER 7 fixed-lane comping.

Tool	Description
get_takes(track, item)	List all takes (name + active flag)
get_active_take(track, item)	Get the active take index
set_active_take(track, item, take)	Switch which take plays
explode_takes(track, item)	Explode takes to overlapping items (in place)
crop_to_active_take(track, item)	Keep only the active take
delete_take(track, item, take)	Delete a specific take
select_comp_lane(track, lane)	Play one fixed lane exclusively (lane comping)

Routing (9 tools)

Tool	Description
create_send(src, dest)	Create send between tracks
delete_send(index, send_index)	Remove a send
set_send_volume(index, send_index, db)	Set send level
get_track_num_sends(index)	Count sends from track
set_send_dest_channels(index, send_index, chan)	Route to specific channels
set_send_source_channels(index, send_index, chan)	Set source channels
setup_sidechain_send(src, dest, db)	Create sidechain send
configure_reacomp_sidechain(index, fx_index, use)	Configure ReaComp sidechain
setup_sidechain_compression(trigger, target, fx, db)	Complete sidechain setup

Transport (10 tools)

Tool	Description
play()	Start playback
stop()	Stop playback
pause()	Pause playback
record()	Start recording
get_play_state()	Get current state (playing/paused/recording)
get_cursor_position()	Get edit cursor position (seconds)
set_cursor_position(seconds)	Move edit cursor
get_play_position()	Get playback position (seconds)
toggle_repeat()	Toggle loop mode
get_repeat_state()	Check if looping

Project (15 tools)

Tool	Description
get_project_summary()	Get comprehensive project state in one call
save_project()	Save current project
create_project(name)	Create new project
open_project(path)	Open project file
get_project_path()	Get project directory
get_project_name()	Get project filename
get_project_length()	Get project length (seconds)
get_tempo()	Get project tempo (BPM)
set_tempo(bpm)	Set project tempo
get_time_signature()	Get time signature
set_time_signature(num, denom)	Set time signature
render_project(path, start, end, tail)	Render to audio file
render_region(index, path)	Render specific region
zoom_to_selection()	Zoom to time selection
zoom_to_project()	Zoom to show entire project

MIDI Operations (8 tools)

Tool	Description
create_midi_item(track, pos, length)	Create empty MIDI item
get_midi_item(track, item)	Get MIDI item info
add_midi_note(track, item, pitch, vel, start_beat, length_beats, chan)	Add single note (beats)
add_midi_notes_batch(track, item, notes)	Add multiple notes
get_midi_notes(track, item)	Get all notes
delete_midi_note(track, item, note)	Delete a note
clear_midi_item(track, item)	Delete all notes
set_midi_note_velocity(track, item, note, vel)	Change note velocity

MIDI Utilities (13 tools)

Editing tools for notes that already exist. Every one takes the same optional filter — a pitch range, an onset window in beats from the item start, and a channel — so you can target a phrase without selecting anything by hand. Timing is in beats, pitch in semitones. Each is one undo step.

Tool	Description
transpose_midi_notes(track, item, semitones, ...)	Shift pitch; notes pushed outside 0-127 are left alone, never wrapped
snap_midi_notes_to_scale(track, item, root, mode, ...)	Snap off-key notes onto a scale (named or a custom interval list)
quantize_midi_notes(track, item, grid, strength, swing, ...)	Snap onsets to the project grid, with strength and swing
nudge_midi_notes(track, item, amount_beats, ...)	Shift notes in time; lengths preserved
stretch_midi_notes(track, item, factor, pivot_beat, ...)	Scale timing about a pivot (half-time / double-time)
legato_midi_notes(track, item, mode, voice, ...)	Close the gaps in a line, or set every note to one length
humanize_midi_notes(track, item, timing, velocity, seed, ...)	Seeded, reproducible timing + velocity jitter
strum_midi_notes(track, item, spread_beats, direction, ...)	Roll a chord out into a strum
ramp_midi_note_velocities(track, item, start_vel, end_vel, ...)	Linear velocity ramp across a phrase (crescendo)
scale_midi_note_velocities(track, item, mode, ratio, ...)	Multiply / set / compress velocities
set_midi_note(track, item, note, ...)	Edit one note's pitch, velocity, timing, channel
get_selected_midi_notes(track, item)	Read the notes selected in REAPER's editor
remove_overlapping_midi_notes(track, item, mode, ...)	Trim or delete overlapping same-pitch notes

remove_overlapping_midi_notes is the only one here that can remove notes; the rest only move what is already there. It is flagged destructive so a client can prompt first.

Audio Items (17 tools)

Tool	Description
insert_audio_file(track, path, pos)	Import audio file
get_track_items(track)	List all items on track
get_item_info(track, item)	Get item details
set_item_position(track, item, pos)	Move item
set_item_length(track, item, length)	Change item length
delete_item(track, item)	Delete item
duplicate_item(track, item)	Duplicate item
split_item(track, item, pos)	Split item at position
set_item_mute(track, item, mute)	Mute/unmute item
set_item_volume(track, item, db)	Set item volume
set_item_fade_in(track, item, length)	Set fade-in
set_item_fade_out(track, item, length)	Set fade-out
select_all_items()	Select all items
unselect_all_items()	Deselect all items
get_selected_items()	Get selected items
copy_selected_items()	Copy to clipboard
paste_items()	Paste from clipboard

Markers & Regions (8 tools)

Tool	Description
add_marker(pos, name, color)	Add marker
add_region(start, end, name, color)	Add region
get_markers()	Get all markers
get_regions()	Get all regions
delete_marker(index)	Delete marker
delete_region(index)	Delete region
go_to_marker(index)	Jump to marker
go_to_region(index)	Jump to region start

Automation (8 tools)

Tool	Description
get_track_envelope(track, name)	Get envelope by name
get_envelope_point_count(track, name)	Count envelope points
add_envelope_point(track, name, time, value, shape)	Add automation point
get_envelope_points(track, name)	Get all points
delete_envelope_point(track, name, index)	Delete point
clear_envelope(track, name)	Clear all points
set_track_automation_mode(track, mode)	Set automation mode
arm_track_envelope(track, name, arm)	Arm envelope for recording

FX Parameter Automation (5 tools)

Tool	Description
get_fx_envelope(track, fx, param)	Get/create envelope for any FX parameter
add_fx_envelope_point(track, fx, param, time, value, shape)	Add automation point to FX parameter
get_fx_envelope_points(track, fx, param)	Get all points from FX envelope
delete_fx_envelope_point(track, fx, param, point)	Delete point from FX envelope
clear_fx_envelope(track, fx, param)	Clear all points from FX envelope

Selection & Editing (11 tools)

Tool	Description
undo()	Undo last action
redo()	Redo last undone action
get_undo_state()	Get undo/redo state
select_track(index, exclusive)	Select a track
select_all_tracks()	Select all tracks
unselect_all_tracks()	Deselect all tracks
get_selected_tracks()	Get selected track indices
set_time_selection(start, end)	Set time selection
get_time_selection()	Get time selection
clear_time_selection()	Clear time selection
delete_selected_items()	Delete selected items

Mixing Helpers (6 tools)

Tool	Description
add_mastering_chain()	Add EQ→Comp→EQ→Limiter to master
add_parallel_compression(track, db)	Set up NY compression
create_bus(name, tracks)	Create submix bus
add_eq(track)	Add ReaEQ
add_compressor(track)	Add ReaComp
add_limiter(track)	Add ReaLimit

Advanced (4 tools)

Tool	Description
run_action(action_id)	Run REAPER action by ID
run_action_by_name(name)	Run action by name
get_track_fx_chunk(track, fx)	Get raw FX state data
cut_selected_items()	Cut items to clipboard

Track Indexing

• Regular tracks: 0-based index (first track = 0)
• Master track: Use index -1

"Set the master track volume to -3dB"  → track_index = -1
"Mute track 1"                          → track_index = 1 (second track)

Common Plugin Names

Use these names with track_fx_add_by_name():

Plugin	Name
EQ	ReaEQ
Compressor	ReaComp
Limiter	ReaLimit
Gate	ReaGate
Delay	ReaDelay
Reverb	ReaVerbate or ReaVerb

Third-party plugins use their full name as shown in REAPER's FX browser.

Troubleshooting

"Cannot connect to REAPER"

1. Ensure REAPER is running
2. Ensure the bridge script is running (check REAPER's console)
3. For file mode: verify the bridge directory exists
4. For HTTP mode: check port 9000 isn't blocked

"Track not found"

• Track indices are 0-based
• Use -1 for master track
• Check track count with get_track_count()

Bridge script won't load

• Lua: Ensure LuaSocket is installed (ReaPack → "sockmonkey")
• Python: Enable Python in REAPER preferences

Slow response

• File-based mode has ~50ms latency per call
• Batch operations when possible (e.g., add_midi_notes_batch)

Environment Variables

Variable	Default	Description
REAPER_COMM_MODE	file	Communication mode (file or http)
REAPER_BRIDGE_DIR	%APPDATA%\REAPER\Scripts\mcp_bridge_data	File bridge directory
REAPER_HOST	localhost	HTTP bridge host
REAPER_PORT	9000	HTTP bridge port

License

MIT License - see LICENSE

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TwelveTake Studios LLC Website: twelvetake.com Contact: contact@twelvetake.com