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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior. The description adds valuable context beyond this: it discloses the billing model ('pague por consulta com crédito pré-pago'), clarifies that the data is public and not sensitive ('ACESSO PÚBLICO', 'não é dado privado nem sigiloso'), and mentions LGPD compliance responsibilities. These are meaningful behavioral traits not apparent from annotations alone.

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 four-sentence paragraph with the core purpose in the first sentence, followed by operational and legal details. Each sentence provides distinct information, but the LGPD clause adds length that is only marginally relevant for an AI agent deciding whether to invoke the tool.

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 simple two-parameter tool without an output schema, the description covers purpose, hosting, payment, and data classification. However, it omits the meaning of the 'completo' parameter and does not describe the return value or response format, which is a notable gap given the lack of an output schema.

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 schema has 0% description coverage, and the description only mentions 'a partir do CPF' to identify the main required parameter. The optional 'completo' boolean parameter is completely unexplained, leaving its purpose and allowed values ambiguous. The description should have compensated for the schema gap but fails to document one of the two parameters.

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 opens with 'Emite a certidão conjunta de débitos federais de uma pessoa física a partir do CPF', which precisely states the action (emits), the resource (joint federal debt certificate), and the scope (individual person via CPF). This clearly differentiates it from the unrelated sibling tools like authenticate and marketplace.

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 clear operational context: 'Hospedado pela plataforma, sem credenciais, pague por consulta com crédito pré-pago' explains the authentication model and pay-per-query requirement. It does not explicitly mention alternatives or exclusions, but since the sibling tools are unrelated, none are necessary.

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