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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds substantially more: a hard cap of 20 addresses and 20 companies, the total-address field name (pontos_total), a 10-lookups-per-day-per-network quota, and the specific free_limit/resets_at error payload. That is rich operational context beyond the structured fields.

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 sentences, each earning its place: purpose/returns, then truncation caps, then quota/error behavior. The most decision-relevant information (what you get back) is front-loaded with zero filler.

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 single-parameter read-only lookup with no output schema, the description covers return shape, truncation, and quota behavior, which is most of what an agent needs. It stops short of describing the address record fields or how to route to sibling lookup tools.

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?

There is a single parameter with 100% schema description coverage, so the schema already carries the meaning and a 3 is the baseline. The description only restates 'CEP (Brazilian postal code)' without adding format, normalization, or validation guidance beyond the schema.

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?

It states a specific resource and return: addresses at a CEP with CNEFE/IBGE coordinates plus the companies registered there. The lookup verb is implicit rather than explicit, and it never names the closely related siblings (consulta_endereco, consulta_cnpj), so an agent gets a clear purpose but no sibling differentiation.

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?

The description explains what comes back but never says when to reach for this tool versus consulta_endereco or consulta_cnpj, nor any precondition such as requiring a valid 8-digit CEP. The only implicit guidance is that it returns both addresses and companies, which hints at scope without stating it.

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