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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so safety is fully covered by structured data. The description adds some value by enumerating what comes back (delivery delay, payment methods, contact), but says nothing about auth, rate limits, or whether the offer data is static or time-sensitive. Moderate credit against a low bar set by the annotations.

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?

One dense sentence, front-loaded with the verb and the resource, then a well-ordered enumeration of the payload. No filler or redundant restatement of the tool name.

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 usefully compensates by enumerating the response fields, and the single optional parameter is fully covered by the schema. The main gap is operational context — when an agent should reach for this versus the faq sibling — which keeps it short of a 5.

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% with a full 18-value enum and a default of 'fr', so the single parameter is already fully documented. The description's only tie-in is mentioning 'supported languages' as returned content, which does not explain how the lang parameter changes the response. Baseline 3 is 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 ('Returns') and a precisely enumerated resource: the three ISBN packs (simple, barcode, premium), their USD/FCFA prices, inclusions, delivery delay, payment methods, languages and contact. This is far more specific than the sibling names (faq, get_order_link, get_required_book_info), but it never explicitly distinguishes itself from them, so it falls short of a 5.

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?

No explicit when-to-use or when-not-to-use guidance is given, and siblings are never named as alternatives. Usage is only implied by the payload description — an agent can infer this is the pricing/offer lookup versus faq or get_order_link, but must make that inference itself.

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