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

Annotations already declare readOnly, openWorld, idempotent, and non-destructive behavior. The description adds useful context beyond that: it is a 'live GET against the public IBGE Malhas API' and returns the mesh in the requested format. This reinforces and slightly extends the annotation information without contradicting it.

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-organized with clear sections for themes, biome codes, examples, routing to alternatives, and behavior. It is longer than strictly necessary because it repeats some enum values already in the schema, but every section earns its place by clarifying usage or adding non-obvious details.

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 and rich annotations, the description covers the core needs: what the tool does, what themes exist, how to use codigo for biomes, when to use ibge_malhas instead, and behavioral safety. It does not explicitly explain whether codigo is required for each non-biome theme, but the 'listar' theme and examples mitigate that gap.

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%, so the baseline is 3. The description adds genuine value on top: it maps biome codes to names (1=Amazon through 6=Pantanal), provides example combinations of tema and codigo, and shows how to use resolucao. This goes beyond the schema's generic 'código específico do tema' phrasing.

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: 'Gets thematic geographic meshes from IBGE.' It clearly distinguishes the tool from its administrative counterpart by explicitly routing administrative mesh requests to ibge_malhas, so an agent can tell exactly what this tool covers.

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 guidance is explicit: it lists all supported themes, gives concrete examples for common cases, and explicitly states 'Use a different tool when: Administrative meshes' with the target sibling tool named. This tells the agent both when to use this tool and when to switch.

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