rtc_aliquota_referencia

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

With no annotations, the description carries the behavioral burden and it does disclose an important non-obvious behavior: in 2026 it returns test rates (CBS 0.9%/IBS 0.1%) and notes the definitive rate depends on the RFB/TCU/Senado process. It does not describe output shape or error handling, but the central caveat is present.

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?

Thedescription is compact and well organized: main statement, parameter list, then a prominent warning. It earns its place with useful caveats and has 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 reference-rate lookup with no required params and no output schema, the description covers invocation semantics and the key 2026 behavioral caveat. A minor gap is that it does not state explicitly what the return value look like (percentage, decimal, object), but the singular 'aliquota' and test-rate examples sufficiently imply a rate value.

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 0%, so the description must compensate. It explains all four parameters: esphera values, the dependencies between esphera and the code fields, and the data format/default. It could add more detail about the expected coding system for UF/municipality, but it is well above the schema alone.

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 clearly identifies the resource: the official reference rate valid on the consulted date, and explains the three sphere variants (uniao/uf/municipio). It does not use an explicit verb like 'returns' or 'gets', and it does not explicitly contrast itself with sibling tools, but its purpose is unmistakable.

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?

Gives explicit parameter-level guidance: 'uf' requires codigo_uf, 'municipio' requires codigo_municipio, and 'data' defaults to today when omitted. It also flags a crucial temporal condition for 2026. No alternative-tool routing is provided, but the usage context for this lookup is clear.

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