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

Adds real behavioral context beyond the sparse annotations: aspect ratio is adaptive and the model is fixed by the endpoint. However, for a generative, openWorldHint=true operation it says nothing about cost, latency, or async polling — notable given a sibling media_task_result exists — and produces no return-value expectations.

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 sentences, no filler, with the generative action and image requirement front-loaded and the negative constraint trailing. Nothing is repeated from the schema or title.

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 6-parameter, no-output-schema generation tool the description covers inputs adequately, but omits the lifecycle — whether the call returns a task id, a URL, or whether the agent must poll nexscope_media_task_result. Annotations carry only readOnly/openWorld hints, so that omission is not covered elsewhere.

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%, so the baseline is 3, but the description adds a genuinely new constraint: 'videoType must not be supplied' guards against an invalid field the schema's additionalProperties:true would otherwise permit. It also reinforces that imageUrl is the required primary image rather than an optional reference.

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 ('Generate a Hailuo 2.3 video') and pins the input requirement ('from a required primary image'). The model name separates it from siblings like kling_2_6_video_generation or wan_3_video_generation, but the description never explicitly routes the agent to or away from those 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?

It supplies one concrete usage constraint ('videoType must not be supplied in the request') and implies image-to-video use via the required primary image. It gives no guidance on when to pick this model over the other video-generation siblings, nor any prerequisites about image hosting beyond the schema's 'public URL'.

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