midi-composer-mcp

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notes_to_midi

Write a note sequence to a MIDI file with optional rhythm patterns, accenting, and octave assignment. Supports scales, arpeggios, and melodies.

Instructions

Write a note sequence (scale, arpeggio or melody) to a MIDI file.

Plays the notes in order, one per step_beats. With rhythm (a pattern like 'O.oo.O..' from random_rhythm or hand-written), each step follows the pattern: O = accented note, o = soft note, . = pause (notes are consumed in order and wrap around if the pattern needs more; with sustain=true pauses extend the previous note instead). Octave-less notes are placed by octave_policy: 'nearest' for melodies, 'ascending' for scale runs. Returns the file path and base64 plus the exact note events written.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "notes": "<notes>"
    },
    "name": "notes_to_midi"
  }
}

Input Schema

Name	Required	Default
`notes`	Yes
`rhythm`	No
`step_beats`	No
`tempo`	No
`octave`	No
`octave_policy`	No	nearest
`velocity`	No
`accent_velocity`	No
`sustain`	No
`program`	No
`file_name`	No
`output_dir`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Jun 12, 2026

TDQS

A4.5/5.0

Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the full burden and delivers thorough behavioral details: note playback order, rhythm pattern (O, o, .), sustain behavior, octave_policy, and return of file path, base64, and event list. No contradictions.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is moderately sized and front-loaded with the main action. It includes necessary details on rhythm and octave policy without excessive verbosity, though it could be slightly more compact.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With 12 parameters, no output schema, and no annotations, the description provides a solid overview of behavior, key parameters, and return values. It covers the core functionality well but could elaborate on less common parameters or edge cases.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, so the description must compensate. It explains the key parameters (rhythm, step_beats, octave_policy, velocity, sustain) in context. However, it does not clarify the format of the notes parameter (string vs array) or some defaults like tempo, octave, program, file_name, output_dir.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool's purpose: 'Write a note sequence (scale, arpeggio or melody) to a MIDI file.' This is a specific verb+resource combination that distinguishes it from siblings like chords_to_midi and song_to_midi.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description explains how to use the tool (e.g., playing notes per step_beats, rhythm pattern interpretation, octave_policy suggestions) and what output to expect. It does not explicitly state when to avoid using it, but given the sibling tools, the context is clear.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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