REAPER MCP

Clear all automation points from an FX parameter envelope. Returns: Object with deleted_count.

Delete all MIDI notes from an item. Returns: Object with count of notes deleted.

Clear the time selection.

Configure ReaComp to use sidechain input for detection. Args: track_index: Track index (0-based) where ReaComp is located. fx_index: FX index (0-based) of ReaComp in the FX chain. use_sidechain: True to use auxiliary input (channels 3-4), False for main input. Returns: Object with configuration status.

Copy selected items to clipboard.

Create a submix/stem bus and route specified tracks to it. Args: name: Name for the bus track. source_track_indices: List of track indices to route to this bus. Returns: Object with bus_track_index and routing info.

Add a click track at the end of the track list. It holds REAPER's click source, which follows the tempo map and time signature changes and accents each downbeat. Args: start: Start in seconds. end: End in seconds (default: the end of the project). name: Track name. Returns: track_index, item_index, start, end.

Create an empty MIDI item on a track. Args: position: Start position in seconds. length: Length in seconds. Returns: Object with item info including the new item_index.

Create a new REAPER project. Note: REAPER has no API to name a project that has never been saved, so this server has no way to name one either. The removed `name` parameter never took effect.

Create a send from one track to another. Args: src_track: Source track index (0-based). dest_track: Destination track index (0-based). Returns: Object with send_index.

Crop a media item to its active take, discarding all other takes.

Cut selected items to clipboard.

Delete an envelope point. Args: envelope_name: Envelope name.

Delete an automation point from an FX parameter envelope. Args: point_index: Point index (0-based) to delete.

Delete a media item.

Delete a marker by index.

Delete a MIDI note from an item.

Delete a region by index.

Delete all selected items.

Delete a send from a track. Args: track_index: Source track index (0-based). send_index: Send index (0-based) to delete.

Delete a specific take from a media item. Args: take_index: Take index to delete (0-based). The take is activated first, then removed.

Delete a track. Args: track_index: Track index to delete (0-based). Cannot delete master track (-1).

Duplicate a media item. Returns: Object with new item info.

Explode all takes of a media item in place (each take becomes its own overlapping item).

Find ReaEQ on a track, optionally adding it if absent. Args: instantiate: If True and ReaEQ is not present, add it. Returns: Object with 'ret' = the FX index of ReaEQ, or -1 if not found.

Get the index of the active take of a media item. Returns: Object with 'ret' = active take index (-1 if the item has no active take).

Get information about all tracks in the project.

Get the edit cursor position. Returns: Object with cursor position in seconds.

Get the number of points in an envelope. Args: envelope_name: Envelope name. Returns: Object with point count.

Get all points from an envelope. Args: envelope_name: Envelope name. Returns: points (time, value, shape, shown). A volume envelope adds value_db to each point, and scaling.

Check whether a ReaEQ band is enabled. Args: fx_index: FX index (0-based) of ReaEQ. bandtype: Band type (0=hipass, 1=loshelf, 2=band, 3=notch, 4=hishelf, 5=lopass). bandidx: Band index within that type (0=first). Returns: Object with 'ret' boolean (true=enabled).

Get all ReaEQ band settings in one structured call. Args: fx_index: FX index (0-based) of ReaEQ in the FX chain. Returns: Object with a 'bands' list. Each band has band_index, bandtype, bandtype_name, bandidx, paramtype, paramtype_name, normval, the REAPER-formatted value, and (for gain params) the computed gain_db.

Get or create an automation envelope for an FX parameter. This enables automation of any FX parameter (e.g., a flanger knob in Guitar Rig). The envelope is created if it doesn't exist. Args: param_index: Parameter index (0-based). Use track_fx_get_num_params() to find available parameters. Returns: Object with envelope_name, param_name, point_count, and indices.

Get all automation points from an FX parameter envelope. Returns: Object with list of points (time, value, shown, shape, tension, selected).

Get the current preset name of an FX. Returns: Object with current preset name.

Get list of presets available for an FX. Returns: Object with list of preset names.

Get information about a media item. Returns: Object with item properties (position, length, take info, etc.).

Get all markers in the project. Returns: Object with list of markers (position, name, index).

Get information about the master track.

Get information about a MIDI item. Returns: Object with item info including position, length, note count.

Get all MIDI notes from an item. Returns: Object with list of notes.

Get the current playback position. Returns: Object with play position in seconds.

Get the current playback state. Returns: Object with play state info.

Get the length of the project (end of last item). Returns: Object with project length in seconds.

Get the project name.

Get the project path.

Get a comprehensive summary of the current REAPER project. Returns everything needed to understand the project state and give useful mixing/production advice in a single call. Returns: Object with: - project_name: Name of the project file - project_path: Full path to the project - tempo: Project tempo in BPM - time_signature: {numerator, denominator} - project_length: Length in seconds - track_count: Total number of tracks - tracks: List of track info objects, each containing: - index: Track index (0-based) - name: Track name - volume_d…

Get all regions in the project. Returns: Object with list of regions (start, end, name, index).

Get the current repeat state. Returns: Object with repeat state (true/false).

Get all selected media items. Returns: Object with list of selected items.

Read the MIDI notes currently SELECTED in REAPER's editor for the active take. The escape hatch for "operate on what I've selected": select notes by hand in REAPER, call this to see which they are, then translate that into an explicit value filter (pitch range / beat window / channel) for the transform tools. Read-only, no undo. Returns: {ok, notes:[...], ret} - the selected notes, same shape as get_midi_notes (each note carries item-relative start_beat/end_beat). `index` is REAPER's absolute PPQ-sorted note index, so a partial selection is non-contiguous. Empty selection -> note…

Get indices of all selected tracks. Returns: Object with list of selected track indices.

List all takes of a media item. Returns: Object with 'takes' array (each entry: index, name, is_active) and 'ret' = take count.

Get the tempo at project start as `ret`, and every tempo marker as `tempo_markers`.

Get the current time selection. Returns: Object with start and end times.

Get the project time signature.

Get information about a track. Returns: Object with 'info': guid, name, volume, volume_db, pan, muted, soloed, has_midi, has_audio, fx_names, role.

Get the total number of tracks in the current REAPER project (excluding master track).

Get a track envelope by name. Args: envelope_name: Envelope name (e.g., "Volume", "Pan", "Mute"). Returns: Object with envelope info.

Get the raw state chunk from an FX plugin (includes preset/state data). Useful for reading VSTi state data like Toontrack EZkeys chord progressions. The chunk contains the full serialized state of the plugin. Returns: Object with 'chunk' containing the FX state data string.

Get all media items on a track. Returns: Object with list of items.

Get the master/parent send state of a track. Returns: Object with 'ret' field (1 = enabled, 0 = disabled).

Get the number of sends from a track.

Get the current peak level of a track. Args: channel: Channel (0=left, 1=right). Returns: Object with peak value in dB.

Get the peak hold level of a track (highest peak since meters were last reset). Returns the max peak from a previous playback without needing to be actively playing - play the project, stop, then call this for gain staging. Args: channel: Channel (0=left, 1=right). Returns: Object with peak hold value in dB.

Get the current undo/redo state. Returns: Object with undo and redo descriptions.

Move the edit cursor to a marker.

Move the edit cursor to a region start.

Humanize MIDI: nudge timing and velocity by small random amounts, reproducibly. Each note gets its own timing and velocity offset drawn from a bell curve. Note lengths are preserved (start and end move together) and pitches are never touched. The randomness is seeded, so the same take with the same seed and settings gives identical results every time. Velocities are clamped to 1-127 and counted in clamped; notes pushed past the item end are kept and reported in out_of_bounds. Unlike the other timing tools, a note pushed before the item start is placed at the item start and counted in out_of_…

Insert an audio file onto a track. Args: file_path: Full path to the audio file. position: Position in seconds. Returns: Object with track_index, item_index of the created item, and position.

Insert a new track at the specified index. Args: index: Position to insert track (0-based). If not specified, adds at end. name: Optional name for the new track. Returns: Info about the created track.

Close the gaps in a MIDI line (legato), or set every note to one length. Only note ends move; starts are never touched. "connect" extends each note's end to the next onset and never shortens anything; a gap wider than max_gap_beats is left as a rest and counted in gaps_preserved, and the last note is left alone. "fixed" instead sets every targeted note's length to length_beats. Notes whose new end passes the item end are kept and reported in out_of_bounds. Args: mode: "connect" (extend each end to the next onset) or "fixed" (set every length). voice: connect only. "chordal" extends t…

Measure loudness as REAPER's loudness window does: integrated LUFS, short-term and momentary max, loudness range, sample peak, plus true peak. Target: the master (default), a track, or one item (its track's output over the item, other items muted). start_time/end_time limit it to a range. It runs a render dry run, so it writes no files, puts selections back and adds no undo step. Measuring the master marks the project as modified, even though nothing in it changes. Returns: integrated_lufs, short_term_max_lufs, momentary_max_lufs, loudness_range_lu, sample_peak_dbfs, true_peak_dbtp, …

Measure tonal balance and stereo image: octave-band levels (31.5 Hz to 16 kHz), spectral centroid, tilt in dB per octave, stereo correlation overall and below 150 Hz, side-to-mid level and left/right balance. Same targets and range as measure_loudness. Levels are dBFS with a full-scale sine at 0, as in REAPER. Needs the TwelveTake MCP Analyzer, which --install-bridge installs.

Shift MIDI notes in time by a number of beats (+ = later, - = earlier). Start and end move together, so note lengths are preserved. A note pushed before the item start clamps to it and one pushed past the item end is left there; both count in `out_of_bounds`, not `clamped`. Args: amount_beats: Signed beat shift (0.25 = a 16th later, -1.0 = a beat earlier). 0 = no-op.

Open a REAPER project file. Args: path: Full path to the .rpp file.

Paste items from clipboard at edit cursor.

Pause playback in REAPER.

Start playback in REAPER.

Quantize MIDI note onsets onto the grid (tighten sloppy timing, add swing). Onsets snap to the PROJECT bar/beat grid, not to an offset from the item's own start, and note lengths are preserved: start and end move together. Notes that land past the item end are kept, and one that would land before the item start is placed at it; both are counted in `out_of_bounds` (`clamped` stays 0 here). Args: grid: Grid spacing in beats: 0.25 = 1/16, 0.5 = 1/8, 1.0 = 1/4. Must be > 0. strength: 0.0-1.0. 1.0 snaps exactly onto the grid, 0.5 moves each note halfway there, 0.0 is a no-op. …

Apply a linear velocity ramp (crescendo / decrescendo) across MIDI notes. Velocities interpolate by onset: the earliest note in the filtered set gets start_velocity, the latest gets end_velocity, everything between is linear. Notes sharing an onset (a chord) get the same velocity. Results clamp to 1-127. Args: start_velocity: Velocity at the earliest onset (1-127; out of range clamps, not an error). end_velocity: Velocity at the latest onset (1-127).

Start recording in REAPER.

Redo the last undone action in REAPER. Returns: Object with redo description.

Clean up overlapping MIDI notes (same pitch stacked on itself). Two notes conflict only if they share a pitch AND a channel AND overlap in time, so a chord is never a conflict and notes that merely touch are left alone. "trim" shortens the earlier note to stop where the next begins, losing nothing; "delete" drops one note of each overlapping pair, keeping the louder (ties go to the longer note). Either mode can remove notes: notes stacked on the exact same onset collapse to the loudest, since there is nothing to trim between them, and a trim left shorter than min_length_beats is removed rath…

Render the project's master mix to an audio file. Apart from the path, source and range, the project's own render settings apply: its format (a .wav extension selects WAV), and its normalization, limiter, fades, trim and pad, which the response lists in `processing` (empty when none applies). If the target file already exists, this returns an error unless overwrite=True (which deletes the existing file first). This is explicit because REAPER's own behavior on existing files (prompt vs auto-increment) is a user preference, and the overwrite prompt blocks unattended rendering. Args: output…

Not implemented: this tool always returns an error. Use render_project with the region's start and end from get_regions.

Run a REAPER action by command ID. Args: action_id: REAPER action/command ID number.

Run a REAPER action by its named command id. Named commands (e.g. ReaScripts "_RS12345" or SWS "_SWS_...") are resolved to a numeric command id via NamedCommandLookup before firing. A purely numeric string (e.g. "40297") is treated as a built-in command id and run directly; prefer run_action(action_id) for built-ins. Args: action_name: Named command id (e.g. "_RS12345") or a numeric command id string. Returns: If the named command cannot be resolved, returns {"ok": False, "error": ...} without firing any action.

Not supported: REAPER's API cannot save a named FX preset, so this tool always returns an error. Use get_track_fx_chunk to capture the current FX state.

Save the current REAPER project.

Scale MIDI note velocities: multiply, set to a fixed value, or compress toward a pivot. Results clamp to 1-127. Args: mode: "multiply" (velocity * ratio), "set" (velocity becomes `value`), or "compress" (pivot + (velocity - pivot) * ratio). ratio: Multiply factor (>= 0, no upper cap), or compress amount (0.0-1.0, where 0 collapses every note onto the pivot and 1.0 changes nothing). value: Target velocity for "set" mode (1-127). pivot: What compress pulls toward (1-127), or -1 for the rounded mean of the matched notes' velocities (reported as pivot_used)…

Select all media items.

Select all tracks.

Make a fixed lane play exclusively on a track (REAPER 7 lane-based comping). The track must be in fixed-lane mode (right-click track -> Track lanes). Returns a clear error if it is not, or if the lane index is out of range. Args: lane_index: Fixed lane index to play exclusively (0-based).

Select the MIDI notes matching the filter, as if clicked in REAPER's MIDI editor. Args: selected: False deselects the matching notes instead; with no filter, clears the selection. exclusive: When selecting, deselect every note that does not match. `notes_changed` counts notes whose selection flipped.

Select a track. Args: exclusive: If True, deselect other tracks first.

Set the active take of a media item (which take plays). Args:

Set the edit cursor position. Args: position: Position in seconds from project start.

Set a ReaEQ band parameter. Pass real values by default: frequency in Hz (paramtype 0), gain in dB (paramtype 1), or Q (paramtype 2). Gain is converted to ReaEQ's normalized curve internally; freq and Q are sent raw. Args: fx_index: FX index (0-based) of ReaEQ. bandtype: -1=master gain, 0=hipass, 1=loshelf, 2=band, 3=notch, 4=hishelf, 5=lopass, 6=bandpass, 7=parallel bandpass. bandidx: Band index within that type (0=first). Ignored for master gain. paramtype: 0=frequency (Hz), 1=gain (dB), 2=Q. Ignored for master gain. value: The value, in real units unless …

Enable or disable a ReaEQ band. Args: fx_index: FX index (0-based) of ReaEQ. bandtype: Band type (0=hipass, 1=loshelf, 2=band, 3=notch, 4=hishelf, 5=lopass). bandidx: Band index within that type (0=first). enabled: True to enable, False to disable.

Set the preset of an FX. Args: preset_name: Preset name.

Set the fade-in length of a media item. Args: length: Fade-in length in seconds.

Set the fade-out length of a media item. Args: length: Fade-out length in seconds.

Set the length of a media item. Args: length: New length in seconds.

Mute or unmute a media item. Args: mute: True to mute, False to unmute.

Set the position of a media item. Args: position: New position in seconds.

Set the volume of a media item. Args: volume_db: Volume in dB.

Edit one existing MIDI note in place: pitch, start, length and/or channel. Only the fields you pass change, and at least one is required. (Velocity: set_midi_note_velocity.) note_index is REAPER's PPQ-sorted index from get_midi_notes / get_selected_midi_notes and is unstable - re-read after the edit, since the returned list reflects the new order. Args: pitch: New pitch (0-127). start_beat: New start in beats from item start; length is preserved. A start before the item start clamps there and is counted in out_of_bounds, not clamped. length_beats: New length in beats (> 0…

Set the velocity of a MIDI note. Args: velocity: New velocity (1-127).

Set the destination channels for a send (used for sidechain routing). Args: track_index: Source track index (0-based). dest_chan: Destination channel pair (0=1-2 main, 2=3-4 sidechain, 4=5-6, etc.). For sidechain compression, use 2 to route to channels 3-4.

Set the source channels for a send. Args: track_index: Source track index (0-based). src_chan: Source channel (-1=none, 0=stereo 1-2, 1024+n=mono from channel n).

Set the volume of a track send. Args: track_index: Source track index (0-based). volume_db: Send volume in dB.

Set the project tempo. Args: bpm: Tempo in beats per minute.

Set the time selection. Args: start: Start time in seconds. end: End time in seconds.

Set the project time signature. Args: numerator: Beats per measure (e.g., 4 for 4/4). denominator: Beat unit (e.g., 4 for quarter note).

Set a track as a folder parent or child. Args: folder_depth: 0=normal, 1=folder parent, -1=end of folder.

Set the automation mode for a track. Args: mode: 0=trim/read, 1=read, 2=touch, 3=write, 4=latch.

Set the color of a track. Args: r: Red component (0-255). g: Green component (0-255). b: Blue component (0-255).

Set the record input for a track. Args: input_index: Input index (-1=no input, 0+=hardware inputs, 4096+=virtual MIDI).

Enable or disable the master/parent send on a track. When enabled, the track's audio routes to its parent folder track (or the master if it has no parent). Disable it when a track should only output through its sends (e.g., routed exclusively to a bus). Args: enabled: True to enable, False to disable.

Set the monitor mode for a track. Args: monitor: 0=off, 1=normal, 2=not when playing.

Set the mute state of a track. Args: mute: True to mute, False to unmute.

Set the name of a track. Args: name: New name for the track.

Set the pan position of a track. Args: pan: Pan position from -1.0 (full left) to 1.0 (full right). 0 = center.

Set the phase inversion of a track. Args: invert: True to invert phase, False for normal.

Set the solo state of a track. Args: solo: True to solo, False to unsolo.

Set the volume of a track in decibels. Args: volume_db: Volume in dB (0 = unity gain, -inf to +12 typical range).

Set the stereo width of a track. Args: width: Width value (0=mono, 1=stereo, 2=200% width).

Complete sidechain compression setup: creates send and configures compressor. This is the all-in-one function for setting up sidechain compression. It creates a send from the trigger track to the target track's sidechain input and configures ReaComp to listen to that sidechain. Args: trigger_track: Track that triggers compression (e.g., kick drum = track 0). target_track: Track to be compressed (e.g., bass = track 1). compressor_fx_index: Index of ReaComp in target track's FX chain. send_volume_db: Sidechain send volume in dB (default 0dB). Returns: Object with complete …

Create a sidechain send from one track to another track's FX sidechain input. This creates a send routed to channels 3-4 of the destination track, which is the standard sidechain input for compressors like ReaComp. Args: src_track: Source/trigger track index (e.g., kick drum). dest_track: Destination track index (e.g., bass with compressor). volume_db: Send volume in dB (default 0dB = unity). Returns: Object with send_index and routing info.

Snap off-key MIDI notes onto a scale (fix a wrong note, force a part into a key). Notes already in the scale are left alone; each off-scale note moves to the nearest in-scale pitch, and under `nearest` a tie resolves toward the middle of the selection. A note with no in-scale pitch left inside 0-127 stays put and is counted in `skipped`. Args: root: Root pitch class, 0-11 (0=C, 1=C#, 2=D ... 11=B). mode: Scale name: major, minor, harmonic_minor, melodic_minor, dorian, phrygian, lydian, mixolydian, locrian, major_pentatonic, minor_pentatonic, blues, whole_tone, chromat…

Split a media item at a position. Args: position: Split position in seconds (absolute project time). Returns: Object with info about both resulting items.

Stop playback in REAPER.

Stretch or compress MIDI timing (half-time, double-time, or any ratio). Each targeted note scales as a rigid unit about one fixed pivot: its distance from the pivot and its own length both multiply by `factor`, so the rhythm is preserved and only the speed changes. Notes that land past the item end are kept as-is; one pushed before the item start begins at the item start but keeps its scaled end, so it comes out shorter. Both are counted in `out_of_bounds` (`clamped` stays 0 here). Args: factor: Time scale ratio, must be > 0. 2.0 = twice as long (half-time), 0.5 = half as long (d…

Strum chords: stagger the onsets of simultaneous notes so each chord rolls out. Only onsets move; note lengths are preserved. Args: spread_beats: Total first-to-last onset span within each chord (>= 0; 0 = no-op). direction: "up" strikes the lowest note of a chord first, "down" the highest. chord_window_beats: Onset tolerance for grouping notes into one chord (0 = exact same onset).

Add an FX plugin to a take by name. Args: fx_name: Name of the FX plugin to add (e.g., "ReaEQ", "ReaComp"). Use the exact plugin name as it appears in REAPER's FX browser. Returns: Object with 'ret' field containing the new FX index (or -1 if it could not be added).

Remove an FX plugin from a take. Args:

Get the number of FX plugins on a take. Returns: Object with 'ret' field containing the FX count.

Get the enabled (not bypassed) state of an FX plugin on a take. Args: Returns: Object with 'ret' field (boolean).

Get a list of all FX plugins on a take. Returns: Object with 'fx' array, each entry having index, name, and enabled state.

Get the name of an FX plugin on a take. Args:

Get the number of parameters for an FX plugin on a take. Args:

Get a parameter value on a take's FX plugin. Args: Returns: Object with 'value', 'min', and 'max' for the parameter.

Get the name of a parameter on a take's FX plugin. Args:

Enable or bypass an FX plugin on a take. Args: enabled: True to enable, False to bypass.

Set a parameter value on a take's FX plugin. Args: value: New value (typically normalized 0-1; check min/max via take_fx_get_param).

Toggle repeat/loop mode. Returns: Object with new repeat state.

Add an FX plugin to a track by name. Args: fx_name: Name of the FX plugin to add (e.g., "ReaEQ", "ReaComp", "ReaLimit"). Use the exact plugin name as it appears in REAPER's FX browser. position: Optional insertion position (0-based) in the FX chain. Default -1 adds at the end; 0 inserts at the beginning. Returns: Info about the added FX including its index.

Remove an FX plugin from a track.

Get the number of FX plugins on a track. Returns: Object with 'ret' field containing count.

Get the enabled state of an FX plugin. Returns: Object with 'ret' field (boolean).

Get list of all FX plugins on a track. Returns: Object with 'fx' array, one entry per FX with index, name, enabled and offline, plus fx_count. 'enabled' is False when the FX is bypassed. Normal FX chain only, not input/record FX or master monitoring FX.

Get the name of an FX plugin.

Get the number of parameters for an FX plugin.

Get a specific parameter value of an FX plugin. Returns: Object with value, min, max for the parameter.

Get the name of an FX parameter.

Move an FX plugin to a new position within the same track's FX chain. Args: fx_index: Current FX index (0-based) in the FX chain. new_position: Target position (0-based). 0 = beginning of the chain.

Enable or disable an FX plugin. Args: enabled: True to enable, False to bypass.

Set a parameter value on an FX plugin. Args: value: New value for the parameter (typically normalized 0-1, check min/max).

Transpose MIDI notes by a number of semitones (12 = an octave). A note that would land outside pitch 0-127 keeps its original pitch and is counted in `skipped` instead. Args: semitones: Signed shift; positive is up, negative is down. 0 = no-op. Returns: {ok, notes_changed, clamped, skipped, out_of_bounds, notes:[...]}, where `notes` is the full note list after the transform, re-indexed.

Undo the last action in REAPER. Returns: Object with undo description.

Unselect all media items.

Unselect all tracks.

Zoom the arrange view to show the entire project.

Zoom the arrange view to the time selection.