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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered; the description still adds value by stating it 'saves nothing and charges nothing' and by disclosing the US-only scope, which is a real constraint an agent would otherwise miss. It stops short of describing the returned quote's format or whether prices can vary over time.

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 tight sentences with no filler: the service scope comes first and the read-only guarantee second, which is the right order for an agent deciding whether it is safe to call.

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?

For a one-parameter, non-mutating quote tool this is close to sufficient, and annotations cover the safety dimension. The remaining gap is the absence of any output schema combined with no hint about what the returned price looks like (total only, breakdown, currency), which the description could have covered.

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 0%, so the description carries the burden, and it does clarify that the count refers to the number of ShipNote postcards being printed, stamped and mailed. It does not restate or explain the 1–500 bounds or what a quote for a given count includes, leaving the single parameter only partially enriched.

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?

Concretely names the priced service (printing, stamping and mailing ShipNote postcards) and the geographic scope (within the US), so the agent knows exactly what question this tool answers. It does not explicitly contrast itself with create_draft or list_card_designs, but the purpose is unambiguous on its own.

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 implied by the name and the 'price quote' framing: call it to estimate cost before ordering. There is no explicit when-to-use guidance, no mention of a prerequisite such as an existing card design, and no named alternative for a different kind of quote.

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