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

The description discloses important behavior beyond the annotations: it runs asynchronously, returns a generation_id, and requires polling via get_generation. It also mentions the $0.10 per-swap cost. Although readOnlyHint=false already indicates mutation, the async contract is valuable supplemental context.

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 two concise sentences with zero filler. The core purpose is front-loaded, followed by the pricing and the critical async polling instruction. Every sentence earns its place.

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 there is no output schema, the description compensates by telling the caller to use get_generation to retrieve the result. It covers the essential workflow for a two-parameter async tool. Minor details such as error states or retry behavior are not mentioned but are not necessary for basic 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?

The input schema already documents both parameters with meaningful descriptions (body photo keeps pose/outfit; head photo provides face/hair), giving 100% schema coverage. The tool description adds no extra parameter-level semantics, so the baseline score of 3 applies.

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 states a clear action and resource: 'Swap heads in photos.' The verb 'swap' and noun 'heads in photos' make the core function unmistakable. It does not explicitly distinguish itself from sibling tools like face_swap or ai_body_swap, though the head-specific wording partially does so.

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 gives clear operational guidance: the tool runs asynchronously and the caller must poll get_generation until status is 'completed'. However, it provides no explicit guidance on when to choose this tool over close alternatives such as face_swap, ai_body_swap, or multiple_face_swap.

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