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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds a genuine data-quality trait beyond them: a firstDate past day 1 signals a partial month (recent connection or plan history start), so an incomplete month must not be compared as a full one. Minor cost: firstDate is not in the input schema, so its role as an output field is left implicit.

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, no filler. The metric/scope statement comes first and the interpretation caveat follows, so the agent reads the core purpose before the edge case.

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 does so: metrics per month plus % variation, at total and marketplace level. What is missing is the shape of the response (one row per month? per marketplace?) and the default window behavior beyond the schema's default.

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%: months (default 6, range 2-12) and marketplace (slug with enumerated values) are fully documented in the schema. The description adds nothing about either parameter, so the baseline of 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?

The description names the exact metrics returned (comissão, vendas, pedidos, cliques), the granularity (por MÊS), the derived value (variação % sobre o mês anterior) and the two aggregation levels (total e por marketplace). That is far more specific than the title 'Crescimento mês a mês', but it never names the close siblings (painel_compare_periods, painel_get_trends) that an agent must choose between.

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 statement of when to pick this over painel_compare_periods or painel_get_trends; the use case is only implied by the metric list. The caveat about incomplete months is valuable but is interpretation guidance, not selection guidance.

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