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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered; the description adds genuinely useful behavioral detail by disclosing the size and composition of the result (six styles, three shapes) and that each entry carries a page URL and a studio deep-link.

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 core enumeration is front-loaded in the first clause; the trailing example object is longer than strictly necessary but directly shows how the returned values are consumed in a cast entry, which earns its place.

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 zero-argument, read-only enumeration with an output schema already present, nothing an agent needs is missing — the description even names the enumerations and the shape of each entry.

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?

The tool takes zero parameters, so the baseline is 4; there is nothing parameter-wise for the description to clarify, and it correctly spends its words on return contents instead.

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 resource (Jabbertoon art styles/looks plus body shapes) and enumerates the exact returned values (flat, outlined, soft, storybook, bold, crayon; classic, big head, tall), so an agent can distinguish it immediately from list_characters, list_moves, or get_move.

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?

Usage is implied by the content description — you call this to discover valid look.style/look.shape values before building a cast entry — but it never states when to prefer this over siblings like list_characters or validate, nor any exclusions.

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