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

Annotations declare a non-read-only, non-idempotent mutation, but the description adds genuinely useful behavior the annotations cannot convey: the call is asynchronous and returns status 'generating' rather than final audio, requiring a poll. It does not mention auth requirements, quota limits, or whether repeated calls create duplicate generations (relevant given idempotentHint=false).

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?

Two dense sentences: the async contract and the retrieval path come first, then the voice-selection note. No filler, every clause carries actionable 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?

For an async generation tool with an output schema and fully documented parameters, the description supplies the one thing the schema cannot: that the response is a queued generationId needing a get_generation poll. Nothing essential for correct invocation is missing.

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 100%, so all four parameters are already documented, including the profileId precedence rule. The description only restates the profileId/profileName selection without adding format or constraint detail beyond the schema, which matches the baseline of 3.

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 (generate) and resource (speech) scoped to the user's VoiceLabs voice profiles, which cleanly separates it from transcribe (the inverse operation) and the voice-profile management siblings. An agent can identify the tool without opening the schema.

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 explicit follow-up workflow: poll get_generation with the returned generationId to retrieve the audio URL, and explains how to choose the voice via profileId or profileName. It does not state when *not* to use this tool or contrast it against transcribe, so it stops short of a 5.

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