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

readOnlyHint=true already tells the agent nothing is mutated, and the description confirms the no-side-effect, no-generation nature plus the unit of return (credits). However, it leaves idempotentHint=false unexplained — an agent may wonder why a supposedly pure price lookup is non-idempotent (presumably pricing can change between calls) — and says nothing about whether the quote expires or must be reused.

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?

Two short clauses, front-loaded with what it returns and immediately followed by the caller's obligation. No filler, nothing to cut.

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?

The tool is conceptually simple, an output schema covers the return shape, and the schema documents all four parameters, so the description is close to sufficient. The remaining gap is behavioral: it doesn't say how stale or binding a returned quote is, which matters given idempotentHint=false.

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 description coverage is 100%, including nested reference slot ordering, so the schema carries the parameter burden. The description only implies that model/prompt/parameters drive the price and never says whether references affect cost, adding little beyond the schema.

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 a specific operation — costing a generation in credits — and its key defining property, 'without making it', which separates it from the generate sibling. An agent can tell immediately this is a price-preview call, not a job submission.

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?

The imperative 'Tell the user before generating' gives a concrete trigger: call this prior to generation and surface the number. It implies the alternative (generate) without naming it explicitly, and gives no guidance on when a quote would be unnecessary.

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