Issue an individual coupon code

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

Annotations already declare readOnly=false, idempotent=true, destructive=false, openWorld=true, so the mutation/idempotency profile is covered; the description adds genuinely new context with the required COUPON_ISSUE permission and the instruction to reuse the idempotency key after a timeout. However, with no output schema it never says what is returned (the code itself?) or whether issuance consumes inventory/usage limits on the coupon — material behavior for an issuance tool.

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?

Three short sentences, front-loaded with the core action and precondition, then usage contexts, then the hard constraint and auth requirement. No filler or repetition of schema prose.

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 high-complexity mutation with a required nested cart, 8 parameters, 38% schema coverage, and no output schema, the description is too thin. An agent still lacks guidance on what cart/subject/shipping represent in the issuance flow and what a successful response contains.

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 only 38% across 8 parameters, so the description carries a large burden and does not meet it. It touches coupon_id and idempotency_key (both already documented in the schema) and vaguely gestures at external_reference, but the required nested cart array, subject, shipping, valid_until, and metadata — all of which materially change the call — are unaddressed.

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 and resource ('Create an individual code from an existing coupon') plus the precondition that the coupon must use ISSUED distribution, and rules out a likely misconception ('never creates discount rules'). It does not explicitly name the neighboring tools (quote_single_coupon, redeem_single_coupon, get_coupon_issuance), so the distinction from siblings must be inferred from the quote/issue/redeem wording.

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?

Gives concrete use contexts ('cart recovery, CRM, or individualized delivery') that tell an agent when this is the right call, and the 'never creates discount rules' clause excludes one wrong usage. No explicit when-not or named alternative (e.g., use quote_single_coupon to preview value first), which keeps it below a 5.

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