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

Annotations already cover read-only, idempotent, non-destructive, closed-world, but the description adds real behavioral value beyond them: a 45-second long-poll window, the explicit 'no new work or charge' side-effect guarantee, and the billing note that provider fallback stays within the quoted price. These are traits an agent could not infer from the annotations alone.

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 the key behavior (wait window) and return states, and closes with the punchy 'No new work or charge.' Sentence one is dense with return-field detail that partly duplicates the output schema, but no sentence is pure filler.

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 read-only status tool with an output schema, the description supplies the wait semantics, the state vocabulary, the no-charge guarantee, and the failure-vs-excluded-section distinction, which is enough for correct invocation. The main gap is the unexplained relationship to the start/preview siblings, but nothing critical is missing.

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 description coverage is 0% and the single projectId parameter is never mentioned in the description, so the description does not compensate for the documentation gap as the rubric requires for low coverage. The parameter is nonetheless self-evident from the tool name, keeping this at a baseline 3 rather than lower.

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 conveys a polling/status verb for a video project and enumerates the concrete return states (draft, storyboard_ready, making, ready, needs_attention), so an agent knows what it does. It does not, however, differentiate itself from siblings such as studio_video_start, studio_video_preview, or the generational *_status/*_wait tools, so purpose is clear but unresituated against alternatives.

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?

Usage is only implied: the 'waits up to 45 seconds while rendering' and 'no new work or charge' phrasing suggest this is the safe tool to re-poll after starting a render. There is no explicit when-to-use, when-not-to-use, or named alternative (e.g., versus a plain preview or start call), leaving routing to inference.

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