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

Annotations already declare readOnlyHint and openWorldHint, so 'Read-only' and 'Changes nothing' are largely restatements. The description does add real value beyond them: the data is the live at-cost rate card with zero markup, and it discloses the shape of each model entry (price tiers by quality/resolution/duration/sound plus unit basis).

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?

Densely packed but front-loaded – the read-only guarantee and the resource come first, then filters, then return shape, then the usage trigger. Every sentence contributes; the only mild redundancy is 'Changes nothing' echoing 'Read-only'.

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 convey the return shape, and it does: per-model price tiers with unit basis. Nothing is said about result size or pagination for the unfiltered full list, which is the one gap for a zero-required-parameter 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?

Schema coverage is 0%, so the description carries the burden and does so: it enumerates the allowed kind values (image/video/music/speech/edit) and tells the agent that model expects an exact id. What it omits is whether model accepts partial matches or is case-sensitive.

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 – read every emero model's per-generation cost in USD – with the scope (live at-cost rate card, zero markup) made explicit. No sibling tool does anything similar, so no disambiguation is required.

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 a clear trigger: 'Use it when the user asks what something costs or wants the full price list.' It also explains that filters are optional and how to narrow results. It stops short of naming an alternative or a when-not condition, but none of the listed siblings compete with it.

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