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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds useful behavioral context beyond annotations: it can report fulfillment status, enumerate applicable promotion types, compute adjusted value, and intentionally mirrors the checkout logic — all without contradicting 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?

Two sentences with no filler: the first sentence front-loads the verb, resource, and outcome list, and the second adds the key guarantee that this mirrors the checkout calculation. Every phrase earns its place, making it both compact and informative.

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 read-only evaluation tool with no output schema, the description covers the essential return concepts: fulfillment, applicable promotions, free gifts, and adjusted basket value. It doesn't spell out exact output fields or error conditions, but the annotation coverage and schema completeness keep the remaining gaps minor.

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%, so the input schema already documents all four parameters including country_code, items, locale, and has_tax_id. The description reinforces the basket context and destination-country dependency but adds little parameter-level meaning beyond what the schema provides, so the 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?

The description names a specific verb ('Evaluate'), a precise resource ('a prospective basket'), and the exact scope ('for a destination country'). It also lists concrete outcomes — fulfillment, promotions including free-delivery offers and free gifts, and adjusted basket value — which distinguish it clearly from product-level tools like get_product_promotions.

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 description makes the context explicit: it is for evaluating a prospective basket before checkout, using the same check the checkout runs. It doesn't explicitly name alternatives or state when not to use it, but the basket-level emphasis and the mention of destination-country fulfillment and adjusted basket value give clear application context among the sibling tools.

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