reaper-mcp

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midi_add_note

Add a MIDI note to a specific track's MIDI item by specifying pitch (0-127), velocity (1-127), and note start/end times in absolute project seconds.

Instructions

Add a MIDI note to the MIDI item on a track that starts at item_start_sec. note_start_sec/note_end_sec are absolute project time in seconds. pitch is 0-127 (60 = middle C), velocity is 1-127.

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": {
      "track_index": "<track_index>",
      "item_start_sec": "<item_start_sec>",
      "pitch": "<pitch>",
      "velocity": "<velocity>",
      "note_start_sec": "<note_start_sec>",
      "note_end_sec": "<note_end_sec>"
    },
    "name": "midi_add_note"
  }
}

Input Schema

Name	Required	Description	Default
`pitch`	Yes
`channel`	No
`velocity`	Yes
`track_index`	Yes
`note_end_sec`	Yes
`item_start_sec`	Yes
`note_start_sec`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Jul 10, 2026

TDQS

B3.4/5.0

Behavior3/5

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

With no annotations, the description must disclose behavior. It explains parameter ranges (pitch, velocity, time) but does not mention effects on existing notes, undo behavior, or required item existence.

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?

Two sentences, no redundancy, front-loaded with purpose. Every word earns its place.

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

Completeness2/5

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

Given 7 parameters, no output schema, and no annotations, the description lacks crucial context: requirement for existing item, return value, and mutation implications.

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

Parameters3/5

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

Schema coverage is 0%, so description must compensate. It explains pitch (0-127, 60=middle C), velocity (1-127), and note_start/end_sec as absolute time, but omits track_index and channel meanings.

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 action (add a MIDI note) and the resource (MIDI item on a track, identified by track_index and item_start_sec). It distinguishes from siblings like midi_add_item.

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

Usage Guidelines2/5

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

The description provides no guidance on when to use this tool versus alternatives, nor does it mention any prerequisites or exclusions.

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