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

Beyond the lone openWorldHint annotation, it discloses the 60-credit charge, the refund condition, the single retry, the equal cost of regeneration, and the 2–5 minute processing time. These are concrete operational details that materially affect invocation decisions.

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?

The description is compact and front-loaded with the operation and input choices, followed by cost, failure handling, regeneration, and latency. The example is useful, and there is no filler or repeated wording.

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?

It covers the central workflow and unusually useful operational behavior, but important invocation gaps remain for a six-parameter tool with no output schema. In particular, it does not document the required identifier, several parameters, or whether the 2–5 minute operation returns a job that should be monitored with wait_for_job or list_jobs.

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?

The prompt example and the distinction between initial creation and `regenerate` compensate somewhat for the schema's 17% description coverage. However, the required `id` is not explicitly identified as a mascot or clip identifier, and `name` and `max_credits` receive no semantic explanation.

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 clearly states the action and resource: adding a motion to a clip mascot, clarified as an uploaded mascot animated as video. It also explains the new-take use case, but does not explicitly distinguish the tool from siblings such as animate_mascot or create_mascot.

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 actionable guidance to supply either a preset `motion` or a descriptive `prompt`, and explicitly says to set `regenerate` when making a new take of an existing clip instead. It does not explain when to prefer this tool over sibling animation tools or when a preset is preferable to a prompt.

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