get_cotacao

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

With no annotations provided, the description carries the behavioral burden and largely meets it: it discloses that a missing date defaults to the last available business day and that the output contains buy/sell values. It doesn't state what happens with a user-supplied weekend/holiday date or mention rate limits, but for a read-oriented quote look-up the core behavior is reasonably disclosed.

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?

Compact and front-loaded: the purpose line comes first, followed by a tight param note in monospace grouping format. Every sentence earns its place, and the currency list and date format are presented economically.

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 two-parameter, no-output-schema quote look-up, the description covers purpose, accepted values, output composition, and date defaults. The only gaps are unspecified behavior for an explicitly supplied non-business date and the exact numeric output format, both minor given the tool's simplicity.

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 0% — the schema properties carry only titles and defaults — so the description must fully compensate, and it does. It enumerates the exact accepted currency codes (USD, EUR, GBP, JPY, CHF, CAD, AUD) and specifies the date format ('aaaa-mm-dd') plus its default fallback logic, adding substantial meaning the schema lacks.

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?

States a specific verb+resource: the official PTAX quotation of a currency against the Real, with buy/sell values. This clearly distinguishes it from sibling rate tools like get_selic, get_cdi, and get_ipca, which return interest-price indexes rather than exchange rates.

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?

Documents the data parameter's default behavior (falls back to a recent business day), which guides effective use. However, it never states when to prefer this over the sibling historico_cambio (historical exchange tool) or converter_taxa, nor when not to use it. It also doesn't specify whether the date must be a business day when explicitly provided.

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