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

With no annotations, the description carries the full behavioral burden. It does disclose two things an agent genuinely needs: the output shape (compra y venta en pesos) and the cost ("2 crédito(s)"), which is a real consumption signal for a paid API. It says nothing about data freshness/update frequency, source reliability, error behavior, or whether the credits are charged on failed calls — gaps that matter for a metered read tool.

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?

One front-loaded sentence: purpose, scope, enumerated options, then cost as the trailing clause. Every element earns its place — the enum list saves the agent from inferring valid values and the cost note is decision-relevant. No filler, no repetition of the title.

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 single optional enum parameter with no output schema, the definition covers what is returned (buy/sell in pesos), the filter semantics, and the credit cost — enough to invoke it correctly. The remaining shortfall is operational context: no indication of how current "actual" is or where the rate comes from, which matters for a financial data tool.

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 baseline is 3, but the description adds real meaning beyond the schema: it expands the cryptic enum tokens into human-readable concepts, mapping "bolsa" to "MEP (bolsa)" and "contadoconliqui" to "contado con liquidación". That disambiguation of jargon is value the raw enum does not provide.

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 ("Devuelve la cotización actual del dólar en Argentina") and states the scope precisely: one exchange house or all of them, with the seven supported values enumerated. No sibling tool (comprar_creditos, ejecutar, validar_cbu, validar_cuit, normalizar_telefono_ar) overlaps with exchange-rate lookup, so an agent can place this tool unambiguously.

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 is only implied: "para una casa en particular o para todas" tells the agent that omitting the filter returns everything, which is a useful default hint. There is no explicit when-to-use/when-not-to-use guidance, no mention of when a narrow query is preferable, and no alternatives named (none of the siblings compete, but the definition doesn't say so).

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