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

With no annotations, the description carries the behavioral burden, and it does disclose one meaningful constraint: results are limited to Verified-plan companies, and ostensibly only 'visible' contacts. It says nothing about authentication, failure modes when the company is not Verified, or result limits.

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?

A single front-loaded sentence with no filler — the resource and its key restriction are stated immediately. Every word earns its place.

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?

An output schema exists, so return values need not be explained, and the plan restriction is noted. However, the only input parameter is undocumented and no error or eligibility behavior is described, leaving gaps for a tool whose main gate is plan-based.

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 0% and the sole required parameter (cnpj) has no prose description in either the schema or the description. 'de uma empresa' only weakly implies the parameter identifies a company; format and expected value are left entirely undocumented.

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 a specific verb and resource ('Retorna os contatos visíveis de uma empresa'), making it clear this is a read operation returning contact records. It does not, however, distinguish itself from siblings like get_company_details or list_companies, which an agent must infer.

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?

It names a gating condition — 'apenas plano Verified' — which tells the agent when the call will succeed. Beyond that, there is no guidance on when to prefer this over get_company_details or other lookup siblings.

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