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

Beyond the annotations (readOnlyHint=false, destructiveHint=false, openWorldHint=true), it discloses that the call is paid, runs asynchronously in the background, and that dry_run produces a price. The quota and 'refused images don't count' rule are exactly the kind of behavioral context annotations cannot carry; only the fate of previously generated images is unstated.

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?

Dense and front-loaded: cost first, then effect mapping, then limits, then execution mode. The telegraphic style ('Paid (casting images)', 'remakes body and sheet (2)') is efficient but slightly compressed enough to require a second read.

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 an async, paid mutation with no output schema, the definition covers cost, side effects, limits and execution mode. It stops short of saying how to follow the background run (e.g., get_run_status), which is the one operational gap.

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 0%, so the description must carry the load, and it does for most parameters: it maps look vs outfit vs body_type to concrete regeneration effects and explains dry_run as a pricing preview. series_id is never mentioned and the empty-string defaults (meaning 'no change') are not explained.

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?

States a specific verb (recast) and resource (character id, a to h) plus a scoping constraint (before their first episode) that distinguishes it from sibling recast_lead. An agent can tell what the tool does and which characters it applies to without opening the schema.

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?

Gives explicit preconditions (before first episode), a quota rule (at most 2 per character, refused images don't count), and which edit type triggers which regeneration count. It never names recast_lead as the alternative for lead characters, so the sibling routing is left to inference.

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