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

With no annotations provided, the description carries the full disclosure burden. It clearly conveys this is a read-only listing operation ('Lista') and discloses the returned fields plus that the coupon appears only 'quando existe'. It doesn't disclose sorting behavior, pagination/limite semantics, or empty-result handling, leaving some behavioral gaps.

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 sentences with zero filler. The first front-loads the action and return fields; the second gives concrete usage examples. Every sentence earns its place and the key information appears first.

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?

Fairly complete for a search/listing tool: the schema covers all parameters, the description covers return fields and typical queries, and the optional-coupon condition is disclosed. Minor gaps — sorting order and empty-result behavior — don't block correct invocation.

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 coverage is 100%, so the input schema fully documents all four parameters. The description adds marginal value by reinforcing desconto_minimo through the 'promoções acima de 50%' example, but otherwise doesn't extend parameter meaning beyond the schema — baseline 3 for high coverage is appropriate.

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 (lista) and resource (produtos em promoção no Mercado Livre Brasil), and enumerates the returned fields (preço atual, preço de tabela, percentual de desconto, cupom). The example queries clarify its intent and implicitly differentiate it from siblings melhor_cupom (coupons) and quedas_de_preco (price drops), though the siblings are not named explicitly.

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 concrete trigger examples ('o que está barato em eletrônicos', 'promoções acima de 50% de desconto') that tell an agent when to invoke. However, it doesn't explicitly state when not to use it or name the alternative tools and their selection conditions — the differentiation from melhor_cupom and quedas_de_preco is left to inference.

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