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 adds substantial operational context beyond them: an edge-cache TTL of up to 6 hours, the note that deadlines/prices are recomputed per request, and the `Cache-Control: no-cache` and `x-origem-cache` (hit/miss/bypass) mechanics. It also discloses the 50-document cap and the free-vs-paid content split — genuinely useful behavioral detail.

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?

Front-loaded with what is returned before moving into pricing and cache behavior, and each sentence conveys distinct information. The cache-controle details are slightly heavy but remain relevant and do not obscure the core purpose.

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 return-value burden and does so reasonably — listing the document fields, the 50-item cap, and free/paid access. Combined with the cache semantics, an agent has enough to call it correctly, though the relationship to the sibling document-access tools is left implicit.

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 is a single parameter with 100% schema description coverage ('id da compra (vem da busca)'), so the schema already carries the semantics. The description adds no syntax or format detail for the id beyond what the schema states, making the baseline 3 appropriate.

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?

States a specific verb+resource: the ficha (record) of a purchase plus its documents, detailing returned fields (titles, types, pages, availability) and a cap of 50 documents. Clear on what it does, but it does not name or differentiate itself from near-neighbors like documento, documento_acesso, or meus_compras, leaving the agent to infer the boundary.

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 implies usage by noting the query is free while content access is paid per document, and the schema notes the id 'vem da busca' — a hint that this follows a search. However, it never explicitly says when to choose this over sibling tools such as documento or meus_compras, so routing guidance is only implied.

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