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. The description adds meaningful context beyond that: the data is sourced from Brazilian search trends, retail calendar dates, and visitor searches, and it is explicitly 'hoje' (today), clarifying freshness and provenance. It still omits any note on rate limits, result size, or timezone.

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 sentences, front-loaded with the core scope and data sources, followed by a usage hint. No filler, no repetition, and the parenthetical efficiently conveys provenance.

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 rich annotations, a fully documented single optional parameter, and no output schema, the description supplies the key missing context: what the data represents (trending topics and best offers), geographic and temporal scope, and a use case. It stops short of describing return structure or result limits, which would help given the absence of an output schema.

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%, with the single parameter por_tema already documented as 'Ofertas por tema' (1-10, default 5). The description's phrase 'melhores ofertas de cada um' hints at per-theme grouping but adds no operational detail beyond the schema, 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?

States a specific resource and scope: trending topics in Brazil today with the best offers for each. A specific verb is implicit ('returns/lists'), and the topical focus distinguishes it from generic offer search siblings, though the description never names those alternatives.

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?

Provides one usage scenario, 'Bom para "o que está em promoção hoje"', which implies when to reach for it. It does not say when to use buscar_ofertas or ofertas_da_categoria instead, nor any exclusions or prerequisites.

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