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

Annotations already declare idempotentHint=true and destructiveHint=false, yet the description still adds meaningful context: an accepted job consumes one API export allowance (a cost), and idempotencyKey re-identifies the same request across retries rather than creating a new job. That explains *how* idempotency behaves, which the hint alone does not.

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?

Four tight sentences, front-loaded with the action and return value, then preconditions, then cost, then idempotency. Every sentence adds something, though the second 'uses one allowance' sentence restates the allowance concept already introduced.

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?

With an output schema present, return values needn't be explained, and the description still names exportJobId. An agent has the action, constraints, cost, and retry semantics; only the follow-up polling path (get_mockup_animation_export) is left implicit for this async export tool.

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 only 33%, so the description must carry weight. It does explain idempotencyKey semantics (same key = same request across retries), while quality and variantId are covered by the schema and fps/format are self-evident enums. The gaps (fps trade-off, format selection) are minor, but the compensation is partial.

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: 'Starts an MP4/WebM export of a saved mockup animation and returns exportJobId.' The word 'saved' and the returned job id distinguish it from preview_mockup_animation and point toward get_mockup_animation_export for polling, though no sibling is named explicitly.

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 states the preconditions for server exports (opaque background, duration under thirty seconds, available allowance), which is real gating guidance, but it never says when to pick this over preview_mockup_animation or export_promo_video, nor what to do after the job is accepted. Usage is implied rather than routed.

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