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

Annotations already declare readOnly, idempotent, and non-destructive, so the safety profile is covered. The description adds genuinely useful behavior beyond that: the closed set of status values (queued, processing, completed, failed, cancelled) and the fact that download URLs are signed for 7 days, which tells the agent links expire and must be refreshed.

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 tight sentences with no filler. It is slightly back-to-front — leading with the return payload rather than the action — but the content is dense and every clause (status enum, three URL types, 7-day signing) earns its place.

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 no output schema, the description must describe return values, and it does so reasonably: status semantics, the outputs object, and the three URL variants. It still leaves some gaps — what 'credits' and 'progress' contain, and behavior for an unknown video_id — but it is close to complete for a one-parameter read.

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% for the single video_id parameter, so the schema already carries the parameter documentation and the description adds nothing about id format or sourcing. Baseline 3 applies when the schema does the heavy lifting.

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 resource (a video) and enumerates exactly what is returned — status, progress, credits, and completed download links — so an agent can tell it apart from list_videos or create_lyric_video. However, it never states a verb like 'retrieve' and does not differentiate itself from wait_for_video, which is presumably the polling alternative.

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 when-to-use guidance at all: no statement that this is the call to poll after submitting a render, and no mention of wait_for_video as the alternative for blocking until completion. The agent must infer the usage pattern entirely from the return-value list.

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