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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false, and destructiveHint=false, covering the safety profile. The description adds a real semantic caveat ('Returned numeric codes belong to Receita, not IBGE'), which is useful domain context, but it says nothing about result shape, ordering, or pagination 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?

Three short sentences, front-loaded with what is looked up, with no redundancy. The caveat sentence is well-placed but the middle usage sentence is somewhat loosely attached to the rest.

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?

No output schema exists, yet a read-only lookup with fully described parameters needs little more; the description conveys the domain meaning of returned codes, which compensates for the missing output schema. The only real gap is sibling disambiguation.

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 schema already documents q, tipo, limit, and codigos, giving a baseline of 3. The description adds no syntax or format detail beyond the schema and only obliquely touches semantics via the Receita/IBGE code note.

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?

States a specific verb ('Find') and concrete resources (city names, state codes, activities, and other Radar CNPJ references), so an agent knows it's a reference/lookup tool. It does not differentiate itself from the sibling list_cnaes, which appears to cover the CNAE case, leaving slight ambiguity about which tool to pick.

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?

Gives one actionable usage rule ('For tender filters, use the city name and state'), which is genuinely helpful context. However, it never states when to prefer this over overlapping siblings like list_cnaes or the consulta_* family, so routing guidance is only implied.

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