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

With no annotations, the description carries the full burden and does well: it explains what the tool returns (coupon, savings, verifiable/conditional status) and adds a critical caveat that conditional coupons must not be presented as guaranteed discounts. This goes beyond a basic summary, though it does not mention side effects or failure modes.

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?

The description is two sentences with no filler. The first sentence front-loads the core function and output, and the second sentence adds an essential semantic warning about conditional coupons. Every sentence earns its place.

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 low-complexity tool with one fully documented parameter, the description covers the return values and the key caveat about conditional discounts. It lacks a comparison to sibling tools and detailed output structure, but nothing critical is missing for correct basic 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?

The input schema already describes the single parameter 'produto' fully (URL or MLB id), and the tool description only repeats that same information. Since schema description coverage is 100%, the description adds no additional parameter semantics beyond the baseline.

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 action ('devolve o cupom') and resource ('melhor cupom para um produto'), and clearly defines the input format (link or MLB id). It does not explicitly contrast with sibling tools, but the function is unambiguous.

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?

The description gives no guidance on when to use this tool versus buscar_promocoes or quedas_de_preco. The intended use is implied by the input and output, but there is no explicit when-to-use/when-not-to-use instruction.

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