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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false. The description adds valuable context by stating it is a 'live GET against the public IBGE Localidades API' and that it 'Returns a Markdown table,' which enriches the behavioral profile beyond the structured annotations.

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 well-structured with a leading purpose statement, concise feature bullets, examples, sibling-tool routing, and a behavior note. Every section earns its place and no unnecessary filler is present.

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 list tool with two optional enumerated parameters, an output schema, and annotations covering safety, the description is complete. It discloses the API source, the Markdown table return format, filtering and sorting behavior, and exactly when to delegate to sibling 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?

Schema coverage is 100% and both parameters already have descriptions and enums. The description adds practical meaning by mapping region names to codes, explaining sort fields in plain language, and giving concrete examples such as regiao='NE' and ordenar='sigla', which helps the agent use the parameters correctly.

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 opens with a specific verb and resource: 'Lists all Brazilian states from IBGE.' It further differentiates from siblings by naming ibge_municipios and ibge_localidade as alternatives for municipalities and locality details, so an agent can clearly tell this tool apart.

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 'Use a different tool when' section explicitly excludes municipalities and locality-detail cases, pointing to the correct sibling tools. Examples also show when to call with no parameters, with a region filter, or with a sort field, making invocation conditions clear.

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