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

Annotations only cover openWorld/idempotent/destructive hints, so the description's disclosure that this is async, returns the queued generation rather than the finished video, and consumes generation quota is genuinely valuable. It stops short of warning that repeat calls are not idempotent and would burn quota again, or of describing failure behavior.

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, front-loaded with the async/queued behavior and quota cost before defaults. The title sentence largely restates the schema's own title description, which is the only wasted motion.

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 need no explanation, and the description covers the critical async/quota semantics. Remaining shortfall is the undocumented generateDocument flag and no caution about double-triggering renders given idempotentHint=false.

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 14% (only title is documented), so the description must compensate: it supplies defaults for resolution, width, height and fps ('FHD, 1920x1080 and 30fps') that appear nowhere in the schema, and clarifies the title's dual effect. The gap is generateDocument, which is unexplained in both places.

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?

Opens with a specific verb and resource: 'Start an asynchronous video render for a project.' That distinguishes it cleanly from siblings like generate_document, get_project, publish_project, and retry_video_segment_script_generation without needing to name them.

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?

The async nature ('does not wait for the rendered video') and the quota cost imply when this is appropriate, but there is no explicit routing to alternatives (e.g. generate_document vs video render) and no when-not guidance. Usage is inferable rather than stated.

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