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

Adds substantial context beyond the annotations: credit costs (~16 for both sheets, ~8 per single-sheet call), that the original skin is left unchanged, and that the new skin folder is written beside the original with identical file names so the rig animates it. The non-destructive claim is consistent with destructiveHint=false. Return payload details (what the concept call hands back besides concept_id) are not spelled out, keeping it off a 5.

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?

Front-loads the eligibility caveat, then the operation, then the cost/workflow trade-off — a logical order with no filler sentences. The heavy parenthetical nesting (rig explanation, credit figures) makes it harder to scan than it needs to be, which costs it a point.

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 8-parameter, non-idempotent generation tool with no output schema, the description covers cost, side effects, output location, and the two-call workflow an agent must orchestrate. What remains thin is the shape of the response itself (what the images/sheets look like in the result), though get_generation_result-like siblings may handle that.

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 100%, so the baseline is 3; the description earns more by explaining the intended parameter workflow — concept_only first, then the returned concept_id on the follow-up call — which ties two parameters together in a way the schema does not. It does not elaborate on secondary parameters like outline or new_skin_name beyond what the schema already says.

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 and resource ('New skin for a Spine-rigged character') and then describes the actual mechanism: painting a concept over front/side/back views, then repainting parts onto one sheet. It even pins the equivalent editor action (Character skins → Reskin…), so an agent knows exactly what operation this is and what it produces.

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?

Explicit guidance on the two modes: a single call produces both sheets, or use concept_only to show the concept first and then call again with its concept_id. It also states preconditions (beta/invited accounts; the folder must sit under an attached Spine rig with front/side/back views). It does not name any sibling alternative, so it falls short of a 5.

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