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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds real value by disclosing the possible outcomes (waiting for payment vs. paid) and that the order number is part of the response; it does not cover behavior for an unknown/invalid id, which is the main remaining gap.

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?

A single compact sentence that front-loads the return semantics and only then the origin of the input. Nothing redundant.

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 one required parameter, no output schema and annotations covering the read-only nature, the description is nearly sufficient: it explains what comes back (status and order number). Only edge-case behavior (invalid or unknown order id) is left unspecified.

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% and the single parameter already documents that it is the 'compra' id returned by fechar_compra. The description echoes that provenance but adds no format or usage detail beyond the schema, so 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?

Names a specific resource (a purchase/order) and states exactly what is returned: its situation, either awaiting payment or paid, plus the order number. It also anchors the tool to the sibling that creates the input (fechar_compra), which distinguishes it from ver_catalogo/ver_disponibilidade.

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 phrase 'compra feita por fechar_compra' makes the usage context explicit: call this after closing a purchase to check its status. No alternative tool is named or excluded, but the sequencing guidance is unambiguous.

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