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

Annotations already cover safety (readOnlyHint=true, destructiveHint=false), but the description adds a non-obvious operational fact that matters for agent decision-making: 'Não consome requisições' — calling this does not burn quota, which is not derivable from the annotations. It stops short of disclosing the shape of the returned series (fields, timezone, whether breakdowns per tool/endpoint are included), and the openWorldHint/idempotentHint=false are left unexplained.

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 short sentences, zero filler, with the resource and its time window front-loaded and the quota-cost caveat second. Nothing needs to be removed.

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 and no parameters, the description does a fair job by specifying the aggregation granularity and the quota behavior. It could go further on what the returned daily series actually contains, but for a zero-parameter read-only reporting tool it is close to sufficient.

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?

There are zero parameters, so the schema carries no semantic load the description must compensate for; the baseline applies. The description adds meaningful scope semantics instead — the 30-day window and per-day aggregation — which are fixed behaviors the agent cannot discover from the empty schema.

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 states a specific resource and scope: a consumption statement ('Extrato do consumo') covering the last 30 days, aggregated by day. It is clearly distinguishable from the CPF/CNPJ lookup siblings, but it does not distinguish itself from the closest sibling 'limite_do_plano', leaving the agent to infer the difference between plan usage and plan limit.

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?

Usage is only implied by the words 'Extrato do consumo' — an agent can guess this is for checking recent usage, but the description never states when to call it versus 'limite_do_plano' and gives no prerequisites or exclusions.

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