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

With no annotations provided, the description carries the full burden and does so well: it discloses the bootstrapping methodology, the exclusion of Focus/IPCA projections, the curve_scope, the typical lack of 1Y/2Y coverage, and the payment_token requirement with cost. This goes far beyond a generic 'get curve' statement.

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?

The description is well-organized with clear sections: what it is, a critical coverage caveat, usage guidance, and argument details. Every sentence adds value, and the most important differentiators are front-loaded.

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 data-retrieval tool with an output schema and no annotations, the description is complete: it covers methodology, coverage limitations, pricing, parameter behavior, and sibling alternatives. An agent has enough context to invoke it correctly without further inference.

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 clearly explains as_of, tenors, quote_side, and payment_token, including defaults, allowed values, and pricing. Four generic parameters (agent_id, session_id, discovery_source, synthetic_identity) are left undocumented, which keeps this from a 5.

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 precisely identifies the deliverable: an IPCA-linked Brazilian sovereign zero-coupon curve bootstrapped from Tesouro Direto NTN-B and NTN-B Principal quotes. It also explicitly distinguishes itself from brazil_yield_curve and brazil_inflation_breakeven in the use-when block, so an agent can select it unambiguously.

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 states when to use the tool ('you need Brazil's real rate curve') and explicitly says not to use it for the nominal curve or breakeven inflation, naming the sibling tools as alternatives. This is exactly the level of routing guidance an agent needs.

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