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

Adds real behavioral context beyond the annotations: it only considers offers valid today, and it explicitly disclaims commerce actions ('não vende, não reserva nem entrega'), reinforcing readOnlyHint. The geographic limitation and the temporal scope are the kind of constraints annotations cannot express. It stops short of describing result ordering/pagination, which is partly covered by the output schema.

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?

Front-loads the core capability, then scope, then examples, then constraints — a sensible ordering with no filler. The example list is slightly verbose but earns its place by showing intent matching.

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 an output schema present and full annotation coverage, the description supplies exactly the missing pieces: what 'top' means (savings vs average), the aggregation axes, the temporal filter, and the hard geographic boundary. Nothing needed to call it correctly is absent.

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%, so the schema already documents limit, market, region, category and ending_today. The description adds the conceptual dimensions (overall/category/market) that map to those params, but introduces no format or syntax detail beyond the schema. 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 verb+resource (lists top deals ranked by savings versus the average) plus the three aggregation scopes (overall, by category, by market). This clearly distinguishes it from siblings like find_cheapest or search_offers, which are filter/lookup tools rather than ranked 'best value' lists.

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?

Gives concrete example utterances ('melhores ofertas agora', 'melhores ofertas de bebidas', 'o que o Giassi tem de bom hoje') that map user intent to the tool, and states a hard geographic exclusion (only Joinville/SC, does not serve other cities). It does not explicitly name a sibling as the alternative for out-of-scope requests, so it stops short of a 5.

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