reaper-mcp

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midi_add_item

Create an empty MIDI item on a track spanning a specified time range, serving as a placeholder for later note insertion via midi_add_note.

Instructions

Create an empty MIDI item on a track spanning start_sec to end_sec. Returns nothing useful yet to reference the item by -- use midi_add_note with the same track/time range, which locates the item itself.

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>",
      "start_sec": "<start_sec>",
      "end_sec": "<end_sec>"
    },
    "name": "midi_add_item"
  }
}

Input Schema

Name	Required	Description	Default
`end_sec`	Yes
`start_sec`	Yes
`track_index`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Jul 10, 2026

TDQS

A3.8/5.0

Behavior3/5

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

With no annotations, the description carries the full burden. It discloses that the return value is not useful for referencing, which is helpful. However, it lacks information on side effects, permissions, or other behavioral traits expected from a creation tool.

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 with two sentences, no fluff, and the key information is front-loaded.

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?

Given the tool's simplicity and lack of output schema, the description covers the basic functionality and return value issue. However, it omits parameter details and does not explain what an empty MIDI item entails, leaving gaps for a new user.

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

Parameters2/5

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

Schema description coverage is 0%, and the description only mentions start_sec and end_sec as a time range without specifying units or indexing format. It adds minimal meaning beyond the schema's parameter names.

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 verb 'Create', the resource 'empty MIDI item', and the scope 'on a track spanning start_sec to end_sec'. It also distinguishes itself from the sibling tool midi_add_note by noting that this tool returns nothing useful for referencing.

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 provides guidance on when to use an alternative (midi_add_note) to locate the created item. However, it does not explicitly state when to choose this tool over others or mention exclusions.

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