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

Annotations only declare readOnly=false/openWorld=true/idempotent=false/destructive=false; the description adds real behavioral context beyond them: credit consumption tied to the authenticated ViewMax account, the Ultra ViewMax C1 daily fair-use pool, that omitted duration/resolution/aspect_ratio are billed at mode defaults, and that the call is asynchronous and must be polled. It does not restate what the idempotency_key schema field already covers.

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?

Four dense sentences, front-loaded with the action and return value, then mode derivation, then billing, then the follow-up call. No filler and nothing buried.

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 correctly supplies the return contract (task_id plus the wait_for_task polling instruction) and the billing/account context an agent needs before spending credits. Gaps remain around the audio and source_video_duration_seconds parameters and model selection, but the core workflow is complete.

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 9% (just idempotency_key), so the description must compensate, and it does for mode, image_urls/video_urls, duration, resolution and aspect_ratio, including that defaults are resolved via get_video_model and billed at those values. It leaves model, prompt, audio and source_video_duration_seconds unexplained, so it is not fully complete.

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+resource: 'Create a video generation task and return its task_id.' That immediately distinguishes it from siblings like generate_image, generate_music and generate_speech, and the return value is named up front.

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 gives explicit mode-selection logic (image_urls -> image-to-video, video_urls -> video-to-video, else text-to-video) and routes the agent to get_video_model for defaults and wait_for_task for polling. It never states when video generation is the wrong sibling (e.g., vs generate_image), but the operational guidance is otherwise strong.

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