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

The description provides substantial behavioral detail beyond annotations: it is asynchronous, returns a generation_id, requires polling get_generation until completed, and specifies cost and duration limits. Annotations only indicate readOnlyHint=false and openWorldHint=true, so this added context is highly valuable for correct invocation.

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 three concise sentences: purpose, cost/duration, and async flow. Each sentence carries necessary information with no filler, and the most critical operational detail (poll get_generation) is clearly stated.

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 paid async operation, the description covers the essential flow: how to launch, how to retrieve the result, and the cost. It does not mention failure modes or explicit alternatives, but given the schema's completeness and the polling instruction, it is mostly sufficient for an agent to invoke the tool correctly.

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 100%, and each parameter (face, video, consent) already has clear descriptions in the schema. The tool description adds no additional parameter-specific meaning, 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 the specific action 'Swap faces in videos', which clearly identifies both the verb and resource. It is distinguishable from siblings like face_swap or ai_head_swap because it explicitly targets videos, though it does not name those alternatives.

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 no explicit guidance about when to choose this tool over similar ones (e.g., face_swap, ai_head_swap, gif_face_swap). It implies the use case through the purpose but lacks any 'use this when' or 'avoid when' instructions, leaving the AI to infer based on the name alone.

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