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

Annotations already mark the operation read-only and idempotent, and the description adds genuinely non-obvious behavior: the asymmetric month convention (initial month excluded, final month included) and the conditional outputs when valor or incluir_valores are set. These are exactly the behavioral quirks that would cause wrong results if left undisclosed.

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?

Three short sentences, front-loaded with the core purpose, then branching into the two conditional behaviors. Every sentence earns its place; the date convention and the operational hint 'puxar os índices crus' are high-value density.

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?

The description is solid on core semantics but leaves real gaps: pro_rata is unexplained, the meaning of the NENHUM enum option is unclear, and with data_final optional an agent is left guessing the default period. With no output schema, the return shape is also undisclosed.

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?

With 0% schema description coverage, the description carries the full burden and largely pays it: it explains that valor triggers a corrected-value result, incluir_valores triggers monthly variations, and it pins the meaning of the date pair via the month convention. However, pro_rata (a boolean that plausibly controls pro-rata correction) is never mentioned.

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?

'Consulta de índice oficial' names a specific verb and resource, and the description defines the exact computation: accumulated correction factor between two dates under the BACEN/IBGE convention (initial month excluded, final month included). This scope cleanly separates it from sibling calculo_* tools, which address other domains like rent or FGTS.

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 makes the tool's domain (official index correction) clear enough that an agent can infer when to pick it over calculo_aluguel or calculo_fgts, but it never states an explicit when-to-use or when-not-to-use rule and names no alternative tool. Usage context is implied rather than stated.

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