Taxas oficiais do Brasil

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It excels here by disclosing that the call incurs a REAL payment of $0.01 USDC on Base mainnet — a critical trait an agent must know before invoking, since it has actual financial consequences. It could additionally describe return format or failure behavior, but the cost disclosure is a substantial and well-placed transparency win.

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, zero waste. The first sentence front-loads the purpose (real-time official Brazilian rates with concrete examples) and the second delivers the essential operational caveat (the $0.01 USDC payment). Every word earns its place, and the critical cost warning is not buried.

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 zero-parameter query tool with no annotations and no output schema, the description covers the essential ground: what it queries (Selic, CDI, commercial dollar) and the non-obvious cost of invocation. The only gap is the unspecified return format, but given the simplicity of the tool and the strong cost disclosure, this is a minor omission rather than a blocking one.

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 tool has zero parameters and an empty schema, so the rubric baseline of 4 applies. There are no parameters for the description to document, and the description correctly adds no redundant parameter information. Nothing is missing on this dimension.

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 ('consulta') and a precise resource ('taxas oficiais brasileiras em tempo real') with enumerated examples (Selic, CDI, dólar comercial). This clearly differentiates it from siblings like verificar_cnpj, verificar_cep, validar_cpf, and business_intelligence, which concern entirely different domains. An agent can immediately know what this tool does and when it applies.

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 purpose is clear enough that an agent can infer when to use it — whenever official Brazilian rates (Selic, CDI, dollar) are needed. However, there is no explicit when-to-use or when-not-to-use language, and no alternatives are named. The sibling differentiation is implicit via domain, not explicit in the text.

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