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

Annotations already declare readOnly, idempotent, and non-destructive behavior. The description adds meaningful behavioral context beyond annotations: the specific open-data endpoint path and the 15-minute cache, which alerts agents to potential data staleness.

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?

Three short sentences, each earning its place: the main functionality, the endpoint reference, and the cache behavior. No fluff or repetition of schema details.

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 a rich output schema, complete parameter descriptions, and safety annotations, the description covers the remaining essentials: purpose, endpoint, cache, and use case. It is adequately complete for an agent to invoke correctly, though it could optionally mention the 365-day window or pagination, both already present in the schema.

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?

The input schema has 100% parameter description coverage, so the schema fully explains each parameter. The description's 'intervalo informado' phrase loosely reinforces the date-range parameters but adds no additional semantic value beyond the 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 opens with a specific verb and resource: 'Lista ARPs' whose vigência ends within a given interval. This clearly differentiates it from siblings like compras_arp_listar or compras_arp_consultar by focusing on the end-of-vigency date range criterion.

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?

It provides a clear use context: 'Permite ao gestor identificar atas próximas do vencimento.' This tells the agent when this tool is relevant, though it does not explicitly state exclusions or name alternative sibling tools.

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