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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered. The description adds genuinely new behavioral context: the call is free, it requires an e-CNPJ-signed request, and it spells out the exact signed-text payload. It stops short of describing auth failure modes or the response shape.

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?

Compact and front-loaded, opening with the scope and cost before the signing mechanics. The fragment style ('Free, company only.') is terse but not wasteful, and every clause carries information.

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?

With no output schema, the description carries the return-value burden and does so reasonably by describing the credential set it returns. Signing and auth requirements are included, leaving only the exact response structure undescribed, which is a minor gap for a read tool.

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%, so all three parameters are already documented in the schema. The description restates the signed_text format ('KYA Brasil: agents <cnpj>' + 'at: <ISO time>'), which mirrors the schema rather than adding syntax beyond it. Baseline 3 is correct when the schema does the heavy lifting.

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 what is returned – 'Every credential ever registered for your CNPJ, any status, whoever held the certificate' – which is more specific than the tool name alone. 'Company only' distinguishes it from the kya_person_agents sibling. It lacks an explicit verb like 'list' or 'get', but the returned resource is unambiguous.

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?

'Free, company only' implies when to reach for this over the person variant, but no alternative is named and no exclusion beyond the company scope is given. Usage is implied rather than stated, which is the definition of the minimum-viable 3.

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