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

Annotations already signal a safe, idempotent read, and the description goes far beyond them by documenting the full status state machine (PENDING/GENERATING_*/RENDERING/COMPLETED/FAILED), what each returns, blockedReason handling, and motion clip extras with creditsRefunded. This is exactly the behavioral context annotations cannot carry.

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?

Front-loaded with purpose then packed with status-specific return details, nearly all of which earn their place. Slightly dense run-on sentences around the motion clip clause, but no real waste.

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?

No output schema exists, so the description carries the return-value burden and does so thoroughly: every status outcome, the blocked path with credits fields and topUpUrl, and motion clip return shape are all covered. An agent has enough to call and interpret results correctly.

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% and both params (id/videoId alias) are fully documented in the schema, so the description correctly does not duplicate param syntax. Baseline 3 applies since it adds no param meaning beyond the structured fields.

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+resource ("Get one video's status and details by id") that is unambiguously distinct from the sibling list_videos and the create/generate tools. The scope (single video by id) is explicit and the alias behavior is a small bonus.

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?

Provides concrete workflow guidance: poll while rendering, and "stop polling and resolve it" when blockedReason appears, with the topUpUrl as the resolution path. It does not name list_videos for the alternative listing case, but the when-to-use context is clear.

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