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

Annotations already mark the tool as non-read-only, and the description adds useful cost context ($0.10 per swap). However, it does not disclose output format, behavior when no face is found, multiple-face handling, or whether processing is asynchronous. No contradiction with 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?

A single, well-structured sentence with the operation front-loaded and the cost appended. There is no filler and no unnecessary repetition of schema 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 simple two-parameter image operation, the essential invocation facts are present: source image, target image, and cost. The main gap is the lack of any statement about the return value or response shape, but the operation is straightforward enough that this is a minor omission.

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% for format, but both parameter descriptions are identical, so the schema alone does not indicate which image is the source and which is the target. The description supplies that essential distinction: image is the face source and target_image is the destination person.

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 names a concrete operation ('Put the face from image onto the person in target_image') with clear source and target roles. It is not a tautology, but it does not explicitly distinguish itself from related sibling tools like ai_face_swap_video, gif_face_swap, or multiple_face_swap.

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?

No explicit when-to-use or when-not-to-use guidance is provided, and no sibling alternatives are mentioned. An agent can infer the basic use case from the verb, but it gets no help deciding between this and the many related face/head/body swap tools.

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