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

With no annotations, the description carries the full behavioral burden and does disclose one real behavior — CPF masking by Receita — plus the full faixa_etaria code mapping. It omits pagination, volume of results, error behavior for invalid/missing CNPJ, and whether an 8-digit root returns partners across multiple companies.

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-loads the core purpose then immediately delivers the returned-field list and the code legend. The faixa_etaria enumeration is long but each mapping is load-bearing if the output schema does not decode it; no filler sentences.

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 re-explained, yet the description still usefully decodes faixa_etaria. Missing for a one-param lookup tool: whether a root CNPJ fans out to multiple companies, result limits/pagination, and not-found behavior — meaningful gaps for an agent deciding what to expect.

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 coverage is 0% for the single cnpj parameter, so the description must compensate, and it does: it states the parameter accepts either a CNPJ root or a full CNPJ, a detail absent from the schema. It stops short of specifying accepted formatting (digits only vs punctuation) or length rules.

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+resource: 'Partners (socios) of one company by CNPJ root or full CNPJ', and enumerates the returned fields (names, type, role/qualificacao, entry date, age band). The phrase 'of one company' implicitly separates it from the sibling search_partners, but the sibling is never named, so differentiation is left to inference.

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?

Usage is implied by the input (have a CNPJ, want its partners), and the description supplies the deterministic output. However, there is no explicit when-to-use statement and no exclusion or routing to alternatives such as search_partners for name-based lookups.

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