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

The description adds materially beyond the annotations: it discloses cost (1 from the monthly Gemini allowance), that refused scripts cost nothing, latency (a few seconds), the return value (audio mediaId retrievable via vids_get_media), and that voice tags like [whisper] are spoken rather than read. These facts align with and enrich the non-idempotent, non-destructive, open-world annotations rather than repeating them.

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?

It is dense and nearly every clause carries information: format, use case, limits, tag handling, cost, latency, and return shape. The opening noun-phrase sentence is slightly awkward grammatically, and the usage rationale is embedded mid-sentence rather than front-loaded, but there is no filler.

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 a three-parameter creation tool with no output schema, the description covers what an agent needs: what it produces, the format, cost implications, failure cost, latency, and how to fetch the result. Nothing essential to calling it correctly 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 coverage is 100%, so the baseline is 3, but the description adds real meaning: the script cap of 2500 characters and the semantics of inline voice tags are behavioral details the schema's 'The text to speak.' does not convey. It also reinforces that voice must come from vids_list_voices. The email parameter's fallback behavior is left entirely to the schema.

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 concrete resource and output: a WAV file (24 kHz mono) voiced from a script, using a voice from vids_list_voices. It clearly separates this from the video-producing siblings by framing the audio as a preview ('before making a talking avatar video') or a standalone asset. The only weakness is that the lead is a noun phrase rather than an explicit verb, so the action must be inferred from the title.

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 usage contexts: auditioning a voice or script before a talking avatar video, or reusing the audio elsewhere. It also names the prerequisite sibling vids_list_voices for the voice parameter. It stops short of stating when not to use it versus vids_create_avatar_video or vids_create_video, leaving that inference to the reader.

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