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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description does add one genuinely useful behavioral fact beyond the annotations: the tool does not compute a price but returns a publication/enquiry location. However, with an output schema present, the return-value clarification is partly redundant, so this lands at an adequate 3.

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?

It is short — two sentences — but not well structured: the leading imperative contradicts the sentence that follows it, and the agent must resolve the negation before understanding the tool. Low word count, poor front-loading.

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 output schema covers return values and the annotations cover safety, but for a three-parameter tool with zero schema descriptions, the entry point for the two required parameters (banner, market) and decision_id is left unexplained. Combined with no usage routing, an agent cannot reliably construct a correct call from this description alone.

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 0% across three parameters (banner, market, decision_id), so the description carries the full burden — and it fails. It alludes to the banner's program but never explains what "market" means here (geo? currency? channel?) or what decision_id is for, and decision_id is not mentioned at all. The description does not compensate for the coverage gap.

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 does convey a specific outcome — it returns where the banner's media program publishes rates or takes an enquiry — but it opens with the misleading imperative "Price it" and then immediately negates it ("GSC never prices"). The framing is jargon-heavy ("banner", "GSC", "program") and the agent must reconstruct that this is a routing/lookup tool rather than a pricing tool. It is vaguely rather than precisely stated.

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?

There is no when-to-use guidance relative to the many plausible siblings (check_eligibility, list_packages, gate_transaction, submit_demand). It only distinguishes against GSC, which is not a sibling tool in the list. The agent gets no signal about which of the 18 other tools should precede or follow this one.

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