Índices do Banco Central

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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds meaningful context beyond that: the data source is a live public SGS API and monthly indices also carry accumulated period and 12-month figures. It does not mention caching, rate limits, or what happens when the requested month range predates the series.

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, front-loaded with source and output content, followed by a compact index glossary. The enum list partially duplicates the schema's enum, but appending unit and cadence information makes it earn its space; minor redundancy only.

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?

With no output schema, the description does its part by stating that results include the period accumulated total and 12-month accumulation for monthly indices, and by giving units per index. It still leaves the concrete response shape (field names, time series framing) and error behavior for a date range that exceeds the series unspecified.

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 100%, so the baseline is 3, but the description earns extra credit by explaining what each enum value actually measures and in which unit (e.g. selic_mensal is accumulated monthly % vs selic which is daily %), and by flagging which indices are monthly versus daily, which governs the de/ate and ultimos parameters.

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 names the resource (official Banco Central index values via the public SGS API) and enumerates every available index with its unit of measure, so an agent knows exactly what data comes back. It does not distinguish itself from the nearest functional sibling (corrigir_valor, which also deals with index-based correction), leaving that differentiation implicit.

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?

There is no explicit guidance on when to call this tool versus corrigir_valor or any other sibling, nor any stated preconditions or exclusions. An agent can infer 'use this to fetch raw index values' from the index list, but the description never says so or routes to alternatives.

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