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

With no annotations, the description carries the full burden. It adds useful behavioral context: the data comes from the Falazuki API and is fed daily by the Central Bank, implying freshness. It does not mention output shape, units, or formatting conventions, but for a simple getter this is a reasonable minimum.

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?

Two sentences with no filler: the first states exactly what is returned, and the second explains the source and update cadence. Information is front-loaded and every clause earns its place.

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 zero-parameter read-only getter with no output schema, the description provides the essential selection and invocation context. It could have named sibling tools or clarified the exact meaning of 'current', but the gaps are 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?

The tool has zero parameters and the schema is empty, so there is nothing for the description to clarify. The baseline of 4 for parameterless tools 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 uses a clear verb ('Retorna') and identifies the resource: current Brazilian economic rates (Selic, CDI, IPCA, savings, dollar, euro, minimum wage). It is easy to understand, but it does not explicitly distinguish itself from siblings like get_rates_history or get_focus_expectations.

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 context is implied through 'atuais' and the daily Central Bank update, signaling this is for current rates. However, there is no explicit when-to-use vs. alternatives guidance, so an agent might not realize that historical data belongs to get_rates_history.

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