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

Goes well beyond the annotations by disclosing that the call only enqueues a background job, that it consumes credits, and that completion requires polling wait_for_video_project. Those are exactly the behavioral facts an agent needs and are not derivable from readOnlyHint/destructiveHint/openWorldHint.

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?

Two compact sentences, zero filler. The core purpose is front-loaded and the operational note (cost, background job, polling tool) is appended, which is the right ordering for an agent scanning for what to call next.

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?

An output schema exists so return values need not be explained, and the async lifecycle is covered. Minor omissions remain: no indication of typical job duration or that the 1080p/720p resolution may depend on account tier (only implied via the schema's resolution note).

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 100%, so every parameter (including the nested style.prompt and assets.image_file_path) is already documented in the schema. The description only restates that the audio track is required and the image is optional, adding no format or constraint detail beyond the schema — baseline 3.

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 ('Generates an audio-guided video from a supplied audio track') plus the two modifiers that distinguish it from the other create_video_* siblings: audio track input, optional starting image and visual prompt. An agent can tell it apart from create_video_from_image/create_video_from_text without opening schemas.

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 names the follow-up tool ('returns a project id for wait_for_video_project'), which is the key routing instruction for an async operation. It does not explicitly say when to prefer this over create_video_from_text or create_video_from_image, so it stops short of full when/when-not guidance.

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