Lookup Brazilian postal code (CEP)

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

No annotations provided, so the description must carry behavioral info. It discloses the cost ($0.005) and that coordinates are conditional ('when available'). The lookup nature implies a read operation, but no explicit statement on side effects or auth needs.

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?

The description is a single, information-dense sentence with no redundancy. Every element (enriched CEP lookup, output fields, cost) 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 simple 1-parameter tool with no output schema, the description adequately explains what the tool returns and the cost. A minor gap is the lack of detail on when coordinates are available, but overall sufficient.

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%, and the description adds no extra semantics beyond what the schema already provides ('8-digit Brazilian postal code'). Baseline score of 3 is appropriate.

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 clearly states the tool performs a Brazilian postal code lookup and lists the enriched data returned: full address, IBGE city code, and coordinates when available. This distinguishes it from sibling tools like decode_boleto or lookup_company.

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 context implies usage for Brazilian CEP lookups. The sibling tools cover distinct entities (boléto, NF-e, company, tender), so the tool's purpose is clear. However, no explicit when-not or alternative instructions are provided.

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