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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds genuinely new context beyond them: the response includes the actions each preset produces and the credit cost per clip, and that calling this itself costs nothing.

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?

A single dense sentence front-loads the resource and its enumerated values, then the payload contents, then the cost. The "Free." fragment is terse but carries distinct and useful information rather than filler.

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?

With no output schema, the description must carry the return-value burden, and it does so adequately by naming what each preset entry includes (actions, credit cost per clip). Only the exact response shape/nesting is left unspecified, which is a minor gap for a simple zero-arg read tool.

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 there is nothing for the description to disambiguate; baseline for a no-param tool is 4. The description correctly implies no inputs are needed by presenting this as a plain list.

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 ("List") and resource ("animation-set presets") and even enumerates the concrete presets available (platformer-character, topdown-walk/run/dash/attack/idle), plus what each entry contains. An agent can distinguish this catalog-listing tool from the mutation siblings like generate_animation_set or animate_sprite without opening any 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?

Usage is only implied: an agent can infer this is the browse-before-generate step given the sibling generate_animation_set, and "Free." signals it is a cheap pre-check. However, no alternative is named and there is no explicit when-to-use/when-not-to-use statement.

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