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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely new behavioral context: the call is 'Free' (no credits consumed), which matters for a pricing tool, and it enumerates what the payload contains. It stops short of describing the response shape or size.

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 front-loaded sentence with no filler; the cost/credit angle appears first and the 'Free' tag lands as a useful closer. The embedded list is dense and slightly crammed, but every item corresponds to real returned content.

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 carries the burden of explaining return values, and it does so by enumerating models, credits per length, frames, camera moves, moods and per-tool prices. For a zero-parameter reference tool this is nearly sufficient; only the response structure (e.g. per-tool vs. flat listing) is left unclear.

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 4 applies; the description correctly implies no input is required by framing it as a lookup of what tools accept.

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 states the resource clearly: a catalog of what the Create tools accept (video models, frames, camera moves, moods) and what they cost in credits. The verb is implicit ('what ... accept and cost') rather than an explicit 'returns', but an agent can tell this is a static reference/discovery lookup rather than an action tool. It is distinguishable from the create_* siblings, though it never names them.

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 must infer it should call this before invoking create_video or create_image to learn pricing and options. There is no explicit 'use this when...' statement, no mention of alternatives, and no note that it takes no arguments and is safe to call freely.

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