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

Annotations already cover read-only, idempotent, open-world and non-destructive behavior, so the description only needs added context — and it delivers the important qualifier that coupons currently exist only for AliExpress, the sole store exposing them via API. It also enumerates the returned fields. Pagination and rate-limit behavior are not mentioned, but with an open-world read tool that is a minor gap.

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 compact sentences, front-loaded with what the tool returns, followed by an aside on the AliExpress-only limitation and then filter and use-case hints. The parenthetical is dense but carries real scope information rather than filler.

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 compensates by listing the fields each coupon carries (code, value, minimum purchase, validity, offer), and all three optional parameters are fully documented in the schema. For a simple filtered-list read tool this is essentially complete; only the sibling routing decision is left unstated.

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%: termo, limite and categoria are each documented in the schema itself, including the 1-3 word termo constraint and the default of 10 offers. The description only restates that filtering by product or category is optional, adding no syntax or behavioral detail beyond the structured fields, so baseline 3 applies.

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 verb+resource: returning valid seller discount coupons, each with code, value, minimum purchase, validity and the offer it applies to. It also discloses a key scope fact (today only AliExpress supplies coupons via API). It does not name or contrast with siblings such as buscar_ofertas, which also accepts product terms, so an agent must infer the split.

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 gives a concrete usage scenario ("Bom para 'tem cupom para X?'") and notes the product/category filter is optional, which tells the agent when this tool fits. It stops short of exclusions — nothing says when to prefer buscar_ofertas or ofertas_da_categoria instead, so the routing decision is left partly implicit.

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