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

Adds substantial context beyond the annotations: a new id is created, the original is untouched, and it consumes quota exactly like a fresh generation. This clarifies the cost model and non-destructive relationship to the source track, which the readOnlyHint/destructiveHint flags do not convey on their own.

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 short sentences, front-loaded with the core action, then the cost/id semantics. No filler and nothing repeated from the schema or annotations.

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?

Output schema exists so return values need not be described, and the quota behavior is well covered. But for a 7-parameter tool with low schema coverage, the near-total silence on generation parameters leaves real gaps an agent must resolve by reading the schema.

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 only 29% across 7 parameters, yet the description says nothing about mode, format, bitrate, intensity, wait_seconds, or how duration interacts with the pre-rendered store. Only track_id/duration are indirectly implied; the description does not compensate for the coverage gap.

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 (generate a variation on an existing track), which is clearer than the title alone. It implicitly separates itself from generate_track / generate_track_instant by operating on an existing track, but never names those siblings, so differentiation is inferred rather than explicit.

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?

Gives a clear when-not ('Do not use it to tweak something for free') and a prerequisite (check remaining quota if tight). It stops short of naming the alternative tool for the edit/tweak case (e.g. edit_track), so routing is only partially closed.

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