Find eligible coupons

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

Annotations already declare readOnly=true, idempotent=true, openWorld=true, destructive=false, so the safety profile is covered. The description usefully adds what does NOT happen (no total calculation, no budget reservation, no consumption) and that missing context causes exclusion rather than an error, but says nothing about result shape, ordering, or how many coupons come back.

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?

Four short sentences, front-loaded with the purpose and then the boundaries; nothing is padded. 'public defaults to true' slightly duplicates the schema's own default/description text, a minor redundancy.

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?

For a tool with a large nested context object, no output schema, and no annotation detail beyond safety hints, the description answers 'what rules apply' and 'what happens with missing context' but leaves the return value entirely unspecified. An agent cannot tell whether it gets coupon identifiers, discount descriptions, or eligibility reasons.

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?

Reported schema coverage is 0% across a deeply nested context object, so the description must compensate and only partly does: it frames the whole 'context' parameter as known customer/cart facts and clarifies the omission semantics, which is the single most important behavioral rule for this parameter. Fields like unit_id, brand_id, location, attributes, shipping and pagination get no explanation at all.

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 gives a specific verb and resource ('Discover coupons') plus the matching condition ('whose configured rules match the known customer/cart context'). The negative clauses ('does not calculate final totals, reserve budget, or consume a coupon') implicitly separate it from the quote_*/redeem_* siblings, though no sibling is named directly.

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?

It establishes this as the discovery step rather than the quoting/consumption step, and explains that omitted context silently narrows results. It does not explicitly say 'call this before quote_*' or name an alternative by name, so routing is inferable rather than stated.

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