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

Annotations only declare the safety profile (non-readonly, non-idempotent, non-destructive). The description adds the crucial asynchronous behavior — the call returns a generationId with status 'generating' and the audio is only available later via get_generation — which the agent cannot infer from annotations. The implicit consequence that repeat calls spawn new generations is left unstated, keeping it from a 5.

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 in a logical order: what it does, what happens next, how to pick a voice. No filler, and the follow-up action is front-loaded before the optional voice-selection note.

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?

An output schema exists, yet the description still supplies the one thing the schema can't convey — that the returned generationId is transient and must be polled. For a 4-parameter, single-required-arg tool this leaves no gap that would cause a misinvocation.

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 every parameter is already documented, including profileId's precedence. The description only restates the profileId/profileName choice without adding format, default-behavior, or precedence detail beyond the schema — the baseline 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 and resource ('Generate speech from text') plus the scope ('in one of the user's VoiceLabs voice profiles'), which cleanly separates it from transcribe, get_generation, and the profile-management siblings.

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?

Explicitly tells the agent what to do after the call ('poll get_generation with that id to retrieve the audio URL once it completes') and how to select a voice. It does not contrast itself with the inverse sibling transcribe, but the workflow guidance is concrete and actionable.

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