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

The annotation set is minimal (readOnlyHint false, destructiveHint false), and the description adds useful behavioral context: it "Takes a few minutes," signaling an asynchronous or long-running operation, and it states the consent requirement for using the video and actor likeness. This goes beyond the annotations without contradicting them.

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 compact and front-loaded with the main function. Each sentence serves a purpose: the first states the operation, the second sets time expectations, and the third covers the consent requirement. There is no fluff or repetition beyond the consent point that also appears in the schema.

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 ivo tool with no output schema, the description does not explain what the caller should expect as a result or how to retrieve the completed swapped-actor video. It covers the input and consent side well, but leaves the output/status behavior implicit, which is a meaningful gap given the absence of an output schema.

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%, so the schema already documents all four parameters including consent semantics and source URL origins. The description does not add new parameter-level meaning, which is acceptable given the high schema coverage.

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 verb and resource: "Replaces the creator in an existing video with another actor." This is specific and understandable, though it does not explicitly differentiate itself from the closely related fattly_face_swap sibling.

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 guidance on when to choose this tool over alternatives such as fattly_face_swap or fattly_edit_video. There are no explicit conditions, exclusions, or mentions of alternative tools, so an agent must infer usage solely from the name and general purpose.

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