Códigos geográficos do IBGE

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

Annotations already cover readOnly, idempotent, openWorld and non-destructive. The description adds genuinely new context beyond them: it is a live GET against the public IBGE Localidades API and returns Markdown. It does not discuss rate limits or error behavior, so it stops short of a 5.

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 purpose, then cleanly sectioned into features, code structure, examples and alternatives, which suits the tool's branching input modes. The code-structure bullets partially duplicate the parameter schema, costing some efficiency.

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?

With an output schema present, return values need not be explained. Between the level-decoding rules, the four examples, the named alternatives and the read-only/API/Markdown behavior note, an agent has everything needed to call it 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 coverage is already 100%, so the baseline is 3, but the description adds meaning the schema lacks — the digit-length-to-level mapping (1/2/7/9 digits) and worked examples such as nome="Campinas", uf="SP" that show how nome and uf combine. It stops short of documenting mutual exclusivity between codigo and nome.

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 opening sentence states a specific dual verb (decodes / searches) against a specific resource (IBGE geographic codes), and the 'Use a different tool when' block explicitly names ibge_municipios and ibge_localidade, so an agent can distinguish it from siblings without reading schemas.

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?

Explicit routing is provided: it says when to use this tool (decode a code at any level, resolve name→code) and when not to, naming two concrete alternatives plus the condition that selects each. Nothing is left to inference.

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