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

The description discloses asynchronous execution, the returned generation_id, and the required polling pattern until status is 'completed'. It also mentions cost ('from $0.50'), which is a valuable side-effect detail not present in the annotations.

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 very concise and front-loads the core function. The 'from $0.50.' fragment is slightly abrupt but minor; every sentence earns its place and the overall structure is effective.

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 simple 3-parameter tool with full schema coverage, the description captures the non-obvious asynchronous workflow and provides a clear retrieval path via get_generation. It does not describe error handling or exact response format, but the polling instruction makes the flow sufficiently 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?

The input schema has 100% parameter description coverage, including enum values for duration, so the schema carries the documentation burden. The tool description adds no additional parameter-specific meaning, so the baseline score of 3 is appropriate.

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 primary function ('Animate any photo') with a specific verb and resource. However, it does not differentiate from siblings that also animate photos, such as ai_talking_photo or ai_face_swap_video, so the purpose is clear but not distinguishing.

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 implies the use case: animate a photo, and gives explicit operational guidance to poll get_generation until status is 'completed'. It does not state when to prefer this over related tools or when not to use it, leaving some ambiguity.

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