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

While annotations already mark the tool as read-only and idempotent, the description adds value by disclosing payment-per-query, absence of platform credentials, LGPD compliance, and data controller responsibilities. This goes beyond structured metadata, though it could mention rate limits or response behavior.

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 a single, dense paragraph that front-loads the core purpose and then adds relevant operational and legal context (cost, LGPD, data source). It is economical with words, though breaking it into bullet points could improve scannability.

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?

The tool is relatively simple (2 optional parameters, no output schema). The description covers purpose, data source, and compliance, but omits how parameters should be supplied (e.g., one of CPF/CNPJ required) and what the response contains. It is adequate but not thorough.

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 has two parameters (cpf and cnpj) with zero description coverage. The description does not explain what these fields are for, that at least one is required, or how they map to CPF/CNPJ. With 0% schema coverage, the description fails to compensate, leaving the agent without essential information to correctly invoke the tool.

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 function: 'Solicitar Certidão Negativa da Dívida Ativa (CNDA), consulta em fonte oficial.' It specifies the resource (CNDA from SEFAZ PI) and the action (request/query), and distinguishes itself from generic sibling tools by naming a specific official source.

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 implies usage context (e.g., it's a query to official sources, costs prepaid credit, and handles non-confidential data) but does not explicitly state when to use this tool over alternatives or provide exclusion criteria. It gives some operational details but lacks direct when-to-use guidance.

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