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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower; the description still adds valuable context by pinning geographic coverage to Joinville/SC and clarifying it only consults ('não vende, não reserva nem entrega'). It doesn't cover failure modes for an unknown or expired offer_id, but the behavioral picture is solid.

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, front-loaded sentences: purpose, trigger examples, then coverage and read-only constraints. The example phrasings partially restate the first line but earn their place as invocation triggers, so nothing is wasted.

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 an output schema present, the description need not explain return values, and annotations plus full schema coverage handle safety and parameter form. The only real gap is what happens when an offer_id is stale or not from the covered city, which an agent would have to discover at call time.

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 coverage is 100% with a single required UUID parameter, so the schema already carries the meaning. The description's note that the offer_id comes from another tool largely duplicates the property description rather than extending it with format or error guidance. 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?

States a specific verb+resource ('mostra o detalhe completo de uma oferta'), adds scope ('com o encarte de origem') and a precondition ('já devolvida por outra ferramenta'). This distinguishes it from the discovery siblings like search_offers or find_cheapest, though it never names one explicitly.

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?

Gives concrete trigger phrasings ('mais detalhes dessa oferta', 'qual o encarte dessa oferta') and an explicit when-not: 'só Joinville/SC, Brasil; não serve para outras cidades'. It lacks a named alternative for out-of-coverage requests, which keeps it below a 5.

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