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

Annotations already declare non-destructive, idempotent, open-world behavior, but they say nothing about cost. The description fills that gap precisely: flat price, at most 1 credit by default, and explicitly not billing full media duration, plus the 5-second clip cap. It still omits whether the call is synchronous or returns a job to poll, which is a real gap given the get_job/resume_job siblings.

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, output form and price front-loaded, no filler. The opening is a sentence fragment with no verb, which slightly undercuts the front-loading, but every sentence contributes 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 a 17-parameter rendering tool with no output schema, the description is far too thin. It does not describe what is returned (asset URL? job id?), whether the result must be polled, how the two input modes (fileId vs mediaUrl) differ, or how a preset is chosen without knowing presetId semantics.

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?

With 17 parameters and only 41% schema description coverage, the description carries a heavy compensation burden but adds meaning for only two things: the preset selection and the 5-second cap on clipSeconds. It says nothing about mode, fileId vs mediaUrl, platform, atSeconds, maxCredits, or transcriptionJobId, so more than half the surface is undocumented in both places.

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 the output artifact (a still PNG or a ≤5s clip rendered with the chosen preset) but never states a verb or what it operates on (a video via fileId/mediaUrl). Against siblings like style_preview and burn_captions it does not explain how this preview differs from those, so an agent must infer the distinction from the name alone.

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?

There is no explicit when-to-use statement, no prerequisites, and no named alternative. The presence of style_preview and burn_captions in the sibling list makes the omission costly: the agent is left to guess whether 'preview' is a cheap pre-render check or a styling dry run.

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