Check that the Reaper bridge is alive and report Reaper's version.

Call this first when anything fails — a clean response confirms both the MCP server and the in-Reaper bridge script are running and reachable.

Returns: {pong: bool, reaper_version: str}.

Return the current project's name, length, tempo, cursor position, transport state, and track count.

Returns a dict: {name, length_sec, tempo_bpm, cursor_sec, playing, paused, recording, track_count}.

List every FX plugin Reaper has scanned (VST2/VST3/CLAP/JS).

Reads Reaper's own scan-cache files directly (no bridge round-trip). Use this to find the exact fx_name string to pass to reaper_add_fx_to_track.

Each item: name (pass this to add_fx, e.g. "VST3i: Serum (Xfer Records)"), kind (VST/VSTi/VST3/VST3i/CLAP/CLAPi/JS), is_instrument (bool), filename.

Result is paginated. The response wraps the page in {total, count, offset, has_more, next_offset, items}.

List all tracks with index, name, volume (dB), pan, mute/solo/arm state, and FX count.

Track index is 0-based and is the value every other track tool expects.

Return name, volume (dB), pan, mute/solo/arm, and FX count for a single track.

Insert a new track. Returns the new track's state including its assigned index.

Delete the track at the given index. This is destructive and shifts later indices down by one.

Rename a track. Returns the updated track state.

Set a track's volume fader in dB. Returns the updated track state.

Set a track's pan. Returns the updated track state.

Mute or unmute a track. Returns the updated track state.

Solo or un-solo a track. Returns the updated track state.

Return the master track's volume (dB), pan, mute state, and FX count.

Set the master track's volume fader in dB.

List FX on a track with each FX's index, name, current preset, enabled state, and param count.

FX index is 0-based within the track's chain and is what the other FX tools expect.

Add an FX to the end of a track's chain.

Returns {track_index, fx_index, name}. If the plugin can't be found the call fails — re-check the exact string via reaper_list_installed_fx.

Remove an FX from a track's chain. Indices of later FX shift down by one.

Enable or bypass an FX (enabled=False bypasses it without removing it).

List every preset available for an FX instance, plus the current selection.

Returns {count, current_index, presets:[{index, name}]}.

Switch an FX to a preset by name or by index.

Provide exactly one of preset_name or preset_index. Use reaper_list_fx_presets to discover valid values.

List an FX's parameters with current value, min, and max.

Returns a list of {index, name, value, min, max}. Parameter values are plugin-native (often normalised 0..1) — read min/max before setting.

Set an FX parameter by index or name. Returns {param_index, value, min, max}.

Insert one automation point on a track volume/pan or FX-parameter envelope.

Tip: if the envelope can't be obtained, set the track to read mode first via reaper_set_track_automation_mode(track_index, 'read').

Delete every point on an envelope. Same target semantics as reaper_add_envelope_point.

Set a track's automation mode (trim/read/touch/write/latch/latch_preview).

Set to 'read' for written envelopes to play back.

Arm or disarm a track for recording. Returns the updated track state.

Set a track's record input (audio channel or encoded MIDI input).

Start playback from the edit cursor.

Stop the transport.

If Reaper is recording, the call is refused unless force=true — this avoids ending a take without the user's go-ahead. Ask the user first, then retry with force=true.

Start recording on all armed tracks.

Pause the transport, keeping the cursor where it is.

Move the edit cursor to a time in seconds. Returns the resulting cursor position.

Set the project tempo in BPM. Returns the resulting tempo.

Set the project time selection (the loop/render range) to [start, end] seconds.

Clear the project time selection.

Enable or disable looped playback (repeat over the time selection).

List all project markers and regions.

Each entry: {index, is_region, position_sec, region_end_sec, name, id}. id is the marker/region's displayed number — pass it to delete/goto tools.

Known limitation: name may come back empty even when a marker has a name. REAPER's Python ReaScript build does not marshal the name out-parameter of EnumProjectMarkers, so names set via reaper_add_marker/reaper_add_region show in Reaper's UI but can't be read back here. Identify markers by position/id.

Add a project marker at a time. Returns {id, is_region, position_sec}.

Add a project region spanning [start, end] seconds. Returns {id, is_region, position_sec}.

Delete a project marker or region by its id.

Move the edit cursor to a marker by its id.

List the sends originating from a track.

Each entry: {send_index, dest_track_index, dest_track_name, volume_db, pan, muted}.

Create a send from one track to another. Returns the new send's index.

Set the level of a track send in dB.

Remove a send from a track. Later send indices shift down by one.

List the media/MIDI items on a track.

Each entry: {index, position_sec, length_sec, muted, take_name}. Item index is 0-based within the track and is what the item tools expect.

Create an empty MIDI item on a track spanning [start, end] seconds.

Returns {item_index, position_sec, length_sec}. Add notes with reaper_add_midi_note.

Insert a single MIDI note into an existing MIDI item on a track.

Delete a media/MIDI item from a track. Later item indices shift down by one.

Render the project to disk using Reaper's most recent render settings.

This reuses whatever output path, bounds, and format were last configured in Reaper's Render dialog — set those up once manually first. Writes a file but does not modify the project.

Analyze a rendered mix: local DSP measurements + AI listening feedback.

Two layers. Local DSP (numpy/pyloudnorm) measures the trustworthy numbers — integrated LUFS, loudness range, sample peak, crest factor, clipped samples, per-band frequency balance, and stereo correlation/width/balance. Then (unless include_ai=false) Gemini is given BOTH the audio file and those measurements and returns grounded mix/master feedback with concrete REAPER fixes.

Requires the optional deps: pip install -e .[analyze], and GEMINI_API_KEY in the environment for the AI layer. Pass a reference_path to compare against a pro track.

This reads files and calls an external API; it never modifies the Reaper project.

One-call mix check: quick-export the master mix, then analyze it.

This is the convenient path — no need to pre-configure the render dialog or pass a file. It tells Reaper to render the master mix to a temp file (reusing your project's render codec, e.g. WAV), measures it with local DSP (LUFS, peak, crest, per-band balance, stereo width), then — unless include_ai=false — uploads a small compressed proxy plus those measurements to Gemini for grounded feedback.

Requires the optional deps (pip install -e .[analyze]) and GEMINI_API_KEY for the AI layer. For best results set the project's render source to 'Master mix' and format to a single audio file. Writes a temp render but does not modify the project.

Trigger any Reaper action by numeric command ID (Main_OnCommand).

The escape hatch for actions not yet wrapped as dedicated tools. Look up IDs in Reaper's Actions list (right-click an action → Copy selected action command ID). Marked destructive because arbitrary actions can do anything.