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

Annotations already declare destructiveHint=true, readOnlyHint=false, and openWorldHint=true. The description adds valuable context beyond annotations: the operation is paid, it is restricted to before filming begins, and the new portrait is shown for approval. It could say more about reversibility or cost details, but it meaningfully supplements the safety profile.

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 brief and front-loads the core action. However, phrases like 'lead a|b' and 'cast v2 series' are cryptic, and the final sentence is easy to misread. It is concise but not optimally structured for an agent parsing requirements.

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 destructive, paid mutation with three required parameters and no schema descriptions or output schema, the description is incomplete. It covers timing and approval but omits parameter semantics, what the approval result looks like, and the consequences of the recast. The agent would need to infer too much before invoking it.

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 0%, so the description must compensate for the three undocumented required parameters. It references the lead and a new portrait/look implicitly, but it does not explain `series_id`, the expected format of `lead`, or what `look` should contain. This leaves parameter meaning largely unresolved.

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 specific mutation: paid portrait replacement for the lead. It also distinguishes the operation from the sibling `recast` by noting that on cast v2 series this is a recast with a new look. The awkward notation 'lead a|b' and jargon 'cast v2 series' keep it from being fully clear, but the core purpose is identifiable.

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 gives an important precondition: allowed only before filming begins. That implies when to use it, but it does not explicitly say when to choose this over the sibling `recast` tool or what to do if filming has already started. The approval step is mentioned but not framed as usage guidance.

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