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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds genuinely non-structured behavior: that a query term or filter is mandatory (schema marks zero required parameters) and the scale of the corpus being searched, which explains the constraint.

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?

Front-loaded with the core action and its inputs, followed by the constraint. The closing rhetorical line about a "dump" is longer than strictly necessary but serves to justify the requirement, so it roughly 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?

For a six-parameter read-only search with no output schema, the description covers purpose, inputs and the key precondition. It does not discuss pagination defaults or result shape, but those are handled by the schema's defaults and are not strictly needed to invoke 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?

Schema description coverage is 100%, so the baseline is 3. The description restates the tipo enum and adds one useful nuance (telefone requires DDD), but contributes little beyond what the schema already documents for q, f, uf, page and pageSize.

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 names a specific verb+resource ("Busca empresas") and enumerates the searchable field types (nome, fantasia, socio, telefone, endereco, cnae), so an agent knows exactly what kind of lookup this is. It does not differentiate from any sibling, but no sibling appears to be a competing search tool, so the purpose stands on its own.

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 states a firm precondition: "Exige termo OU pelo menos um filtro", which tells the agent when this call is valid and implicitly when it will fail. The clarifying sentence about scanning 71 million establishments without a filter reinforces the constraint, though no alternative tool is named for unfiltered listing.

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