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

Beyond the generic annotations (readOnly, openWorld, idempotent, non-destructive), the description discloses specific behaviors: it explicitly states the tool does not return price, lists the exact fields returned (idCompra, idItemCompra, etc.), notes the verification date, and mentions the 10-minute cache. This goes well beyond the annotations and helps set expectations about data freshness and content.

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 well-organized and mostly concise, but it contains some redundancy: the warning about not returning price is stated multiple times ('sem valor de preço', '⚠️ Esta tool não devolve preço', 'Nenhum campo de valor'). While this emphasis is understandable, it slightly detracts from conciseness. Structure is otherwise clear with distinct sections for endpoint, warning, alternative, and cache.

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 the presence of a full input schema, output schema (indicated by context signals), and annotations covering safety and idempotency, the description provides sufficient context. It explains the purpose, the exact endpoint, what data is returned (and what is not), and points to the correct alternative for price queries. Nothing essential is missing for an agent to use this tool correctly.

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 provides 100% coverage with detailed descriptions for all parameters (e.g., 'Código CATSER do serviço. Inteiro 4-6 dígitos. Ex.: 27332.'). The tool description adds no additional parameter semantics beyond what's in the schema, so the baseline score of 3 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?

The description clearly states the tool's purpose: 'Lista as compras individuais de um serviço CATSER' with the specific verb 'Lista' and the resource 'compras individuais de um serviço CATSER'. It also explicitly differentiates from the sibling tool by noting it does not return price and pointing to 'compras_pesquisar_preco_servico' for price data.

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 provides explicit guidance on when to use this tool versus the alternative: 'Para preço unitário de serviço use `compras_pesquisar_preco_servico`'. This clearly tells the agent when to choose the sibling tool, implying this tool is for non-price purchase details. It also mentions cache duration and verification date, adding practical usage context.

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