compose

/compose — Create & Edit MIDI Files

Use the Mozart MCP tools to create MIDI files from scratch or edit existing ones.

Quick Start

/compose new_song.mid

Creating a New MIDI File

1. Create with create_midi — set name, tempo, time signature
2. Add tracks with add_track — name them and assign instruments
3. Add notes with add_notes — specify measure, beat, pitch, duration, velocity
4. Save with save_midi — write to disk

Editing an Existing File

1. Load with load_midi
2. Browse with get_measures to understand the structure
3. Edit — use add_notes, delete_notes, transpose, quantize
4. Change tempo/time sig with set_tempo, set_time_signature
5. Save with save_midi

Examples

Create a simple melody

create_midi alias="demo" name="Demo Song" bpm=120 file_path="demo.mid"
add_track alias="demo" name="Piano" instrument=0
add_notes alias="demo" track=0 notes=[
  {"measure": 1, "beat": 1, "note_name": "C4", "duration_beats": 1, "velocity": 80},
  {"measure": 1, "beat": 2, "note_name": "E4", "duration_beats": 1, "velocity": 80},
  {"measure": 1, "beat": 3, "note_name": "G4", "duration_beats": 1, "velocity": 80},
  {"measure": 1, "beat": 4, "note_name": "C5", "duration_beats": 1, "velocity": 90}
]
save_midi alias="demo"

Transpose a track up a perfect fifth

transpose alias="song" track=0 semitones=7

Quantize to eighth notes

quantize alias="song" track=1 grid_beats=0.5

Delete notes in measures 5-8 and rewrite

delete_notes alias="song" track=0 measure_start=5 measure_end=8
add_notes alias="song" track=0 notes=[...]
save_midi alias="song"

Change tempo mid-song

set_tempo alias="song" bpm=140 at_tick=1920

Tool Reference

Tool	Purpose
create_midi	Create a new empty MIDI file
add_track	Add a track with name and instrument
set_instrument	Change a track's instrument
add_notes	Insert notes at measure/beat positions
delete_notes	Remove notes from a measure range
transpose	Shift notes up or down by semitones
quantize	Snap notes to a rhythmic grid
set_tempo	Set/change tempo at a tick position
set_time_signature	Set/change time signature
save_midi	Write MIDI file to disk

General MIDI Instruments (Common)

#	Instrument	#	Instrument
0	Acoustic Grand Piano	24	Nylon Guitar
4	Electric Piano 1	25	Steel Guitar
6	Harpsichord	30	Distortion Guitar
11	Vibraphone	32	Acoustic Bass
13	Xylophone	33	Electric Bass (finger)
16	Drawbar Organ	40	Violin
19	Church Organ	42	Cello
21	Accordion	46	Orchestral Harp
56	Trumpet	73	Flute
60	French Horn	71	Clarinet
65	Alto Sax	68	Oboe

Tips

• Note names follow scientific pitch notation: C4 is middle C
• Beats are 1-based within a measure (beat 1 = downbeat)
• Fractional beats work: beat 1.5 = the "and" of beat 1
• Velocity ranges from 1 (barely audible) to 127 (maximum)
• Always save_midi after editing — changes are in-memory until saved
• Use get_measures to verify your edits look correct before saving