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

No annotations are provided, so the description carries the full behavioral burden. It does disclose the non-obvious cost ($0.005 USDC per call via x402) and implies a read-only data fetch, but says nothing about latency, rate limits, error conditions, or whether the latest month's figure is provisional.

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 tight clauses with no filler; the subject (what data, from whom) is front-loaded and the pricing caveat follows. Slightly more explicit routing would have justified a 5 but nothing is wasted.

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-parameter data fetch with no output schema, the description covers the source, the three returned figures, and the cost, which is enough to invoke it correctly. Minor gaps remain around freshness/provisionality of the current month's reading.

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%: the single 'months' parameter is fully documented with bounds (1-60) and default (12) in the schema. The phrase 'monthly history' corroborates the schema but adds no syntax or semantic detail beyond it, so the baseline 3 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?

States a specific resource and its provenance (IPCA, IBGE via BCB) plus exactly what it returns: latest monthly change, 12-month accumulated, and monthly history. It is clearly distinct from sibling economic indicators like selic_rate and ptax_exchange_rate, though it never names or contrasts those alternatives explicitly.

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 when-to-use guidance, no mention of prerequisites, and no routing between this tool and closely related siblings such as selic_rate or ptax_exchange_rate. Usage can only be inferred from the returned fields.

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