set_mixer

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

Annotations already declare readOnlyHint=false and destructiveHint=false, so the mutation/safety profile is covered. The description adds genuine behavior beyond that: omitted fields stay untouched, volume is on a 0.85 = 0 dB scale, and track_index is ignored for master — the kind of detail an agent cannot infer from annotations.

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?

One front-loaded sentence establishes scope and semantics, followed by a compact bullet list that maps each parameter to its value domain. No redundant or filler text; every line conveys usable information.

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 an output schema present, return values need not be described, and the partial-update contract plus the value ranges make the tool callable correctly. The only shortfall is the unmentioned arm/mute/solo flags.

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%, so the description must carry the load, and it documents volume, pan, sends (keyed by return index), track_type and track_index well. However arm, mute and solo — a third of the parameters — get no mention at all, so compensation is only partial at 8 params and no required fields.

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 opening sentence gives a specific verb+resource ('Set ... a track's mixer controls') plus the key partial-update property ('omitted controls are left alone'). It is distinguishable from read-side siblings like get_mixer and from set_device_param/set_control, though it never names a sibling explicitly.

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 rather than stated: the partial-update note tells the agent it can change one control without touching others, which is useful, but there is no guidance on when to prefer this over set_device_param or get_mixer, and no prerequisites (e.g. whether the track must exist or be armed).

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