tracks_set_instrument

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

Beyond the annotations (readOnly=false, idempotent=true, destructive=false), it discloses that the track retains its name, clips, effects and mixer settings, that the change is undoable with the previous instrument and its sound restored, and that plugin instruments load in the background. These are meaningful behavioral traits an agent could not infer from structured fields.

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?

Three tight sentences, front-loaded with the action and source, followed by preservation and undo behavior. No redundant restatement of the name or schema.

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?

With annotations covering safety/idempotency and no output schema required, the description supplies the remaining essentials: where the instrument comes from, what survives the swap, and that it is reversible. Nothing critical is missing for correct invocation.

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 coverage is 100%, so the baseline is 3, but the description adds real meaning: the instrument value comes from instruments.list and may be a builtin or an installed plugin name, with background loading. The track id/index and optional name semantics are left to the schema, which is acceptable.

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 names a specific verb and resource ('Replace the instrument of a MIDI track') and states the source of the new instrument (instruments.list, builtin or installed plugin). This clearly separates it from siblings like tracks_update, devices_add, and instruments_load_preset.

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?

It gives clear context for when this tool applies (swapping a MIDI track's instrument from instruments.list) and notes plugin instruments are loaded in the background. It stops short of explicit exclusions or naming the alternative tool for non-MIDI/device-router cases.

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