Mixes one chain inside a rack by setting volume, pan, mute, or solo, such as a single Drum Rack pad.
Mix one chain of a rack, e.g. a single Drum Rack pad (get_rack lists them): volume 0-1 like a track fader (0.85 = 0 dB, 1.0 = +6 dB), pan -1..1.
| Name | Required | Description | Default |
|---|---|---|---|
| pan | No | ||
| kind | No | track | |
| mute | No | ||
| solo | No | ||
| chain | Yes | ||
| volume | No | ||
| track_index | Yes | ||
| device_index | Yes |
Changes observed during successful MCP inspections.
v1.3.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full behavioral burden. It usefully adds the volume scale semantics (0.85 = 0 dB, 1.0 = +6 dB) and pan range, which are not obvious. Yet it omits mutation side effects, whether the device must already be a rack, and the effect of leaving mute/solo/volume unset.
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?
Delivered as a single dense sentence with the core operation front-loaded, followed by the practical volume/pan scale. The parenthetical and colon make it slightly run-on but nothing is wasted.
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?
For an 8-parameter mutation tool with no annotations, no output schema, and 0% schema coverage, the description covers volume and pan well but says nothing about mute/solo behavior or return values. It is adequate but leaves clear gaps an agent would want filled.
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% across 8 parameters, so the description must compensate. It clarifies the three most ambiguous params (chain as a rack pad, volume 0-1 with dB mapping, pan -1..1), but leaves kind, mute, solo, track_index, and device_index to inference.
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?
States a specific verb+resource: 'Mix one chain of a rack, e.g. a single Drum Rack pad.' An agent can identify what object is being modified. It names get_rack as the companion for listing chains but does not explicitly differentiate from set_track or set_device_parameters.
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?
Usage is implied via the reference to get_rack ('get_rack lists them'), giving the agent a cue about the prerequisite lookup. However, there is no explicit when-to-use, when-not-to-use, or named alternative among the many sibling set_* tools.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.