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

Annotations already declare readOnly, idempotent, and non-destructive behavior. The description adds meaningful context: it forwards the BCB disclaimer verbatim, names the data source (Olinda OData/PTAX), and warns that quotes only exist on business days with FX closing. No contradiction with 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 organized with clear labels ('Quando usar', 'Quando NÃO usar', 'Retorna', 'Fonte') and every sentence contributes useful information. It is somewhat long, but the structure makes it scannable and there is no 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 simple tool with one optional parameter, an output schema, and safety annotations, the description provides all needed context: purpose, usage decision, return fields, source, disclaimer handling, and availability caveat. Nothing material is missing.

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?

The single parameter 'termo' has 100% schema coverage and is already described with examples ('EUR', 'libra') and optionality. The description only repeats that it accepts a filter term, adding no meaningful semantics beyond the schema, so the baseline score of 3 applies.

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 states a specific action ('Lista') and resource ('moedas com cotação publicada pelo Banco Central'), and specifies the returned fields (símbolo, nome, tipo). It also distinguishes itself from bcb_cambio_cotacao by explicitly saying it is not for cotação values.

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 gives explicit 'Quando usar' guidance: to discover the correct symbol before calling bcb_cambio_cotacao, and explicit 'Quando NÃO usar' guidance: for exchange rates themselves. This clearly routes the agent to the correct sibling tool.

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