generate_startend2video_to_video

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It effectively adds value by disclosing cost implications ('COST WARNING: This tool makes an API call to Vidu which may incur costs'), model-specific defaults for duration and resolution, and constraints like BGM only supported for 4-second videos. This goes beyond what the input schema provides.

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 description is appropriately sized but could be more front-loaded; the cost warning is prominent, but parameter details are listed in a structured 'Args:' section which is clear but somewhat verbose. Every sentence earns its place by providing necessary information, though it might benefit from tighter formatting.

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?

Given the complexity (8 parameters, no annotations, no output schema), the description is largely complete. It covers purpose, usage guidelines, behavioral traits, and detailed parameter semantics. However, it doesn't fully explain the return values ('task_id and video_url') or potential errors, leaving minor gaps in contextual completeness.

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?

Given 0% schema description coverage, the description compensates fully by adding detailed semantics for all 8 parameters. It explains the purpose of 'images' as start and end frames, lists model options with defaults, specifies prompt length limits, details duration defaults and options per model, clarifies seed behavior, resolution dependencies, movement amplitude options, and BGM constraints. This adds significant meaning beyond the bare schema.

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 description clearly states the tool's purpose: 'Generate a video from a pic and prompt.' It specifies the verb 'generate' and resource 'video,' though it doesn't explicitly differentiate from sibling tools like 'generate_img_to_video' or 'generate_text_to_video.' The mention of 'two images: first is start frame, second is end frame' provides some specificity but not full sibling distinction.

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 description includes a clear usage guideline: 'Only use when explicitly requested by the user' due to cost warnings. It doesn't explicitly state when to use this tool versus alternatives like 'generate_img_to_video' or 'generate_text_to_video,' but the cost warning and parameter details (e.g., requiring two images) imply context for usage.

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