updateCoupon

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

Annotations already indicate destructiveHint=true and idempotentHint=true, but the description adds critical context about the partial update (differential merge) behavior and the unit change for discount_amount with coupon_type. No contradictions with 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?

The description is front-loaded with the core purpose and efficiently conveys key usage constraints in a few sentences. While slightly dense, every sentence adds value and there is no redundancy.

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?

Given the tool's complexity with a nested object and multiple parameter interdependencies, the description addresses the most critical behavioral nuance (discount_amount-coupon_type coupling) and provides clear sibling differentiation. It does not cover return values (no output schema), but that is acceptable. The description is sufficiently complete for an update tool.

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?

The schema covers 50% of parameters with descriptions, but the description adds essential semantics beyond the schema: explaining that discount_amount units depend on coupon_type (yen vs %), that delivery_charge does not require discount_amount, and that group_ids are used only when group_limit_type is not 'none'. This compensates for the schema's lack of explicit dependency explanation.

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 clearly states the tool performs a differential merge of existing coupon settings, specifying that only keys included in shop_coupon are updated while omitted keys remain unchanged. It also references sibling tools for creation, deletion, and retrieval, distinguishing itself effectively.

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 provides when-to-use guidance by naming createCoupon for new coupons, deleteCoupon for deletion, and getCoupon for current values. Also warns about the dependency between coupon_type and discount_amount when changing types, offering a clear exclusion.

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