image_to_video

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

With no annotations provided, the description must carry the behavioral transparency burden. It does so admirably by disclosing an estimated duration ('约需 1～5 分钟'), image constraints (JPEG/PNG, max 4.7MB), mode resolutions (720P/1080P), and conditional requirements for tail_image_url and template_id. It stops short of explaining the async nature or result retrieval, but the output schema may cover that.

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 well-organized with a clear one-sentence purpose, followed by structured bullet points for each parameter and mode. It is slightly long but every line adds operational value, with no redundant or filler content.

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 tool with five parameters and multiple modes, the description is remarkably complete. It covers all input constraints, mode-specific behaviors, duration options, and even provides sub-list of template IDs. Since an output schema exists, not describing return values is acceptable. The only minor omission is an explicit statement about whether the operation is synchronous, but the time estimate strongly implies asynchronous.

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 0%, so the description must compensate. It does so fully by explaining every parameter: image_url's format and size, prompt as required, mode's enumerated values with meanings, duration_sec allowed values, and tail_image_url's conditional use. It even lists specific recamera template IDs, going far 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 opens with '图生视频：将静态图片转换为动态视频', which clearly states the tool's purpose: converting a static image into a dynamic video. This is a specific verb+resource combination that distinguishes it from sibling tools like generate_video (likely text-to-video) and image_to_image.

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 details the various modes and their prerequisites (e.g., first_tail requires tail_image_url, recamera requires template_id), giving implicit usage context. However, it never explicitly states when to choose this tool over alternatives like generate_video or image_to_image, lacking a direct comparison or exclusion note.

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