convert_usd_brl

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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds valuable behavioral context beyond annotations: the exact calculation formula, default FX rate and tax divisor, and the environment-variable override mechanism. It does not mention rounding, precision, or error handling, but for a simple read-only conversion this is strong transparency.

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 sentence that front-loads the core action, followed by the formula and default/override information. Every clause earns its place: verb, resource, formula, defaults, and override mechanism. No wasted words.

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 three-parameter conversion tool with full schema coverage and rich annotations, the description is nearly complete. It covers the calculation, defaults, and overrides. It does not explicitly state what the tool returns (a BRL number), but given the absence of an output schema and the obvious nature of the output, this is a minor 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 description coverage is 100%, so the schema already documents each parameter including defaults and env-var overrides. The description adds value by embedding the formula showing how fxRate and taxDivisor are used together, which clarifies the parameters' roles beyond their individual descriptions. This exceeds the baseline of 3 for full schema coverage.

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 verb (Convert) and resource (USD amount to BRL), and includes the exact formula. It clearly distinguishes from all sibling tools, which are listing/pricing/cost tools, none of which do currency conversion. An agent can immediately tell what this tool does.

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 implies usage (when you need a BRL amount from a USD value) but never explicitly states when to use this tool versus alternatives. No alternatives exist in the sibling list, and no exclusions or prerequisites are mentioned. The usage is obvious from the purpose, but the description provides no explicit guidance.

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