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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so the description adds minimal behavioral transparency beyond stating it returns 'informações atualizadas' (updated information). The description does not disclose any additional traits like authorization needs or rate limits. With strong annotations, the description's extra value is limited, meriting a 3.

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 long, front-loaded with the core action, and every sentence provides useful information. No extraneous text. It is concise and well-structured.

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?

Given that an output schema exists, the description does not need to explain return values. It mentions structured data and updated information. The tool has 2 parameters (1 required) and the description covers the use case. It could be slightly improved by noting the finite set of categories/keys (implied by openWorldHint=false), but overall it is sufficiently complete.

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%, meaning the input schema already fully documents both parameters (key and category). The description merely repeats the parameter roles ('categoria e chave especificadas') without adding new meaning or constraints. According to guidelines, baseline is 3 when coverage is high.

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 clearly states 'Recupera dados estruturados do oráculo B2R' (retrieve structured data from the B2R oracle), specifying the resource (oracle data) and action (fetch). It differentiates from sibling tools (calculate_fator_r, query_export_rules, simulate_simples_nacional) which have distinct purposes.

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 explicitly says 'Use quando precisar de dados de mercado, pricing ou métricas atualizados' (use when needing market data, pricing, or updated metrics), providing clear context for use. However, it does not mention when not to use it or suggest alternatives, but given sibling tools cover different domains, this is sufficient.

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