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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), and the description goes beyond them by disclosing return-time behavior: missing periods come back as null, units/frequencies are returned per series, warning fires when a series starts after the requested from, and dataStatus has three enumerated values. It does not say what happens if fewer than 2 or more than 6 codes are supplied, nor how maxPoints truncation interacts with the range.

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?

Five short sentences, front-loaded with the core purpose and the eligibility constraint, then progressively disclosing output semantics. No filler or restatement of the tool name.

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 carries the burden of explaining returns and it does so reasonably: alignment, nulls, units, frequencies, warning, dataStatus. The remaining gap is the shape of each series entry and ordering/truncation behavior, which an agent would still be guessing at.

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% and already documents codes (2–6), from/to (YYYYMM), and maxPoints (2–600, default 120). The description only reinforces the codes range and the meaning of from in the warning sentence, adding little beyond the schema. 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?

"Alinha de 2 a 6 séries pelo período para comparação lado a lado" states a specific verb (align/compare), resource (séries) and scope (2–6 series, side-by-side, period-aligned). It also hard-gates on hasSeries=true. However it never names get_indicator_series, the obvious single-series sibling, so an agent must infer the boundary itself.

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 precondition "Só aceita indicadores com hasSeries=true" is a useful eligibility rule, but the description gives no explicit when-to-use/when-not or alternative routing to get_indicator_series or get_indicator_latest. Usage must be inferred from the multi-series comparison framing.

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