generate_video

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

With no annotations, the description carries the behavioral burden and does well: it discloses per-second credit pricing, which models include audio, a documented failure mode ('Veo I2V intermittently fails its audio pass without one'), and a hard precondition (images must be uploaded via upload_file with real Content-Type). It doesn't cover error handling or what wait=true actually returns, so it stops short of a 5.

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?

The purpose is front-loaded, but the remainder is a single dense wall of arrow-delimited routing text rather than scannable structure. Most sentences carry model-selection value, though the volume partly overlaps with what list_models exists to provide.

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 9-parameter tool with nested model_options and no output schema, the description covers the essentials: destination directory, model-selection guidance, upload prerequisite, and failure caveats. It leaves minor gaps around the blocking-mode return value, but nothing that would cause a wrong invocation.

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 guide adds real meaning to the `model` parameter that the schema's one-line example cannot (which model fits which use case and cost). It also enriches `image_urls` by mandating upload_file, going beyond the schema's bare 'Input image URLs'.

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 opening sentence states a specific verb and resource ('Generate a video'), the backend (kie.ai, 85+ models), and the output location (kie/assets/raw/). It also explicitly routes adjacent work elsewhere ('Extend video→use veo_extend or runway_extend tools'), so an agent can separate it from the extend/upscale siblings without opening a schema.

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 MODEL GUIDE is effectively a when-to-use decision tree: cinematic, budget, fast, lip-sync, avatar, motion control, multi-shot, and image-to-video each map to named models. It names alternatives and their selection conditions (e.g. 'Extend video→use veo_extend'), and points to list_models for exploration.

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