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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so safety is covered. The description still adds real context beyond them: prices are shipping-inclusive and delivery times are destination-dependent, which affects how results should be interpreted. It does not say whether prices are live or cached, 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?

Two sentences, both earning their place: the first enumerates outputs, the second gives the trigger condition. Front-loaded with the resource before the usage hint, with no filler.

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 single-parameter, read-only, closed-world tool with no output schema, the description fully covers what is returned (formats, shipping-inclusive prices, delivery times) and when to call it. Nothing an agent needs to invoke it correctly is missing.

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% and the country parameter already documents the ISO 3166 two-letter format with examples (ES, US, GB). The description only echoes it as 'destination country,' adding no syntax or edge-case detail, so the schema does the heavy lifting and 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 (lists) and a precisely enumerated resource: printed formats (hardcover, softcover), prices including shipping, and delivery times for a destination country. The mention of 'printed book formats' implicitly separates it from order-creation or layout siblings, and an agent can tell what data comes back without opening the schema.

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?

Explicitly says when to use it: 'when the user asks what a printed book costs or how long delivery takes.' That maps cleanly to the two return values. It stops short of naming alternatives (e.g. get_order_status for existing orders) or when-not-to-use conditions, so it is strong but not exhaustive.

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