MIDI MCP Server

Create MIDI

create_midi

Generate MIDI files from structured composition data with chord support, returning base64-encoded MIDI and an interactive piano-roll preview.

Instructions

Generate a MIDI file from structured composition data with chord support. Supports single notes, note arrays (chords), and chord names (5, 6, 7, 9, 11, 13, maj, m, min, dim, etc.). Returns base64-encoded MIDI data and displays an interactive preview with piano-roll notation and playback.

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": {
      "title": "<title>"
    },
    "name": "create_midi"
  }
}

Input Schema

Name	Required	Description	Default
`title`	Yes	Title of the composition
`composition`	No	Composition object with bpm (number), optional timeSignature ({numerator, denominator}), and tracks (array of {name?, instrument?, notes: [{pitch, chord?, beat?, startTime?, duration, velocity?, channel?}]})

Output Schema

Name	Required	Description	Default
`bpm`	Yes
`title`	Yes
`midiBase64`	Yes
`trackCount`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.2.0Aug 2, 2026

TDQS

A4.2/5.0

Behavior3/5

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

With no annotations provided, the description carries the full burden. It discloses that the tool returns base64-encoded MIDI data and shows an interactive preview, which is useful. However, it does not mention any side effects, limitations, or prerequisites beyond the input schema, leaving some behavioral ambiguity.

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

Conciseness5/5

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

The description is concise and well-structured, with two sentences that front-load the main purpose and then provide key details about output and preview. There is no redundant information or filler.

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?

Given the tool's simplicity (2 parameters, output schema present), the description covers the essential aspects: what it does, the output format, and the interactive preview. It does not mention the behavior when composition is omitted (since title is the only required parameter), but this is a minor gap.

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?

The description adds value beyond the input schema by elaborating on the chord support feature, listing specific chord types (5, 6, 7, 9, 11, 13, maj, m, min, dim, etc.). It also clarifies that the composition data must be structured, reinforcing the schema's meaning.

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 uses a specific verb ('Generate') and resource ('MIDI file'), clearly stating the tool's function. It also mentions chord support, which distinguishes it from the sibling parse_chord tool, even though it does not explicitly name it.

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 clearly indicates the tool should be used when generating a MIDI file from structured composition data. However, it does not explicitly mention when not to use it or provide alternatives, such as referencing the sibling parse_chord tool.

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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