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add_midi_note

Adds a MIDI note to an existing MIDI item by specifying pitch, start time, length, and channel, enabling precise MIDI composition within REAPER projects.

Instructions

Add a MIDI note to an existing MIDI item. pitch: MIDI note number 0–127 (60 = middle C, 69 = A4). start/length: seconds, relative to the item's start. channel: MIDI channel 0–15 (use 9 for drums).

Input Schema

NameRequiredDescriptionDefault
pitchYes
startYes
lengthYes
channelNo
velocityNo
item_indexYes
track_indexYes

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv0.1.1

TDQS

B3.3/5.0
Behavior2/5

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

No annotations are supplied, so the description carries the full burden. It conveys that this is an additive mutation on an existing item, but says nothing about failure behavior for invalid indices, whether notes are appended or can collide, or what is returned. That is thin for a write tool with zero annotation coverage.

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 core action is stated first, followed by compact per-parameter notes with no filler. Every line carries information and the format is easy to scan.

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

Completeness3/5

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

With no output schema, no annotations, and 7 parameters, the description covers the musically tricky fields but omits velocity range/default semantics and, critically, the index basis for track_index and item_index. An agent can call it, but may guess wrong on indexing and velocity.

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 the description must compensate; it does so well for pitch (0–127, 60=middle C), start/length (seconds, relative to item start) and channel (0–15, 9=drums). However velocity, track_index and item_index are completely undocumented, leaving 3 of 7 parameters with no semantics anywhere.

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

Purpose4/5

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

States a specific verb and resource ("Add a MIDI note to an existing MIDI item"), which is clearly distinct from siblings like create_midi_item or create_drum_pattern. It doesn't explicitly name those alternatives, so differentiation is implied rather than stated.

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

Usage Guidelines3/5

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

The phrase "to an existing MIDI item" implies the prerequisite that an item must already exist (presumably via create_midi_item), but there is no explicit when-to-use/when-not guidance and no mention of alternatives for bulk note creation. Usage is inferable but not spelled out.

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