List or update media clips on a track, adjusting fades in seconds, gain, mute, loop, position, and length in beats.
Media items on a track. action: list | update. fade_in / fade_out are seconds (REAPER native). position/length are beats.
| Name | Required | Description | Default |
|---|---|---|---|
| loop | No | ||
| mute | No | ||
| action | Yes | ||
| fade_in | No | ||
| gain_db | No | ||
| fade_out | No | ||
| item_index | No | ||
| track_index | Yes | ||
| length_beats | No | ||
| position_beats | No |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full disclosure burden. It adds useful unit context ('fade_in / fade_out are seconds', 'position/length are beats') and names the two actions, but it does not disclose update side effects, mutability of fields, output shape, or error behavior.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is two short sentences with no filler; the action list and unit clarifications are front-loaded. It is concise and readable, though slightly terse given the tool's complexity.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
This is a 10-parameter, two-action tool with no annotations and no output schema, so the description must carry substantial weight. It does not explain which optional properties apply to update, what list returns, or how item_index resolves relative to track_index, leaving important gaps.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 0%, and the description partially compensates by explaining fade units, position/length units, and action values. However, it leaves mute, loop, gain_db, item_index, and the track_index relationship undocumented, so parameter meaning is incomplete.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description identifies the resource ('media items on a track') and the supported actions ('list | update'), giving a clear verb+resource mapping. It distinguishes the tool from sibling concepts like track or midi, though it does not explicitly contrast itself with them.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
No guidance is given about when to choose this tool over alternatives such as track, midi, or reaper_call, nor when to use list versus update. The description implies usage through the resource phrasing but never states selection criteria or exclusions.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.