payments_get_coupon

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

The annotations already declare readOnlyHint, idempotentHint, and destructiveHint:false, covering safety. The description adds no extra behavioral context, such as what is returned, error conditions, or authentication requirements. It does not contradict annotations, but it provides no value beyond them.

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 only two words, 'Fetch Coupon'. While concise, it is under-specified and lacks any structure or elaboration. It does not earn its place because it omits critical details like required parameters or return behavior, making it more of a placeholder than a useful description.

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 that there is no output schema, the description should explain what the tool returns or any notable effects. It does not. It also fails to clarify how to use the required parameters (id and code) together. The annotations cover safety, but the description is incomplete for a 4-parameter tool with no output schema.

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 input schema has 100% coverage with descriptions for all parameters (id, code, altId, altType), so the description does not need to add parameter details. It adds no additional meaning or clarification, which is acceptable given the high schema coverage, but it does not enhance understanding.

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 'Fetch Coupon' states a specific verb and resource, distinguishing it from the sibling list tool 'payments_list_coupons' by singular/plural. However, it is vague and does not clarify whether it fetches by id, code, or both, leaving the operation ambiguous despite the schema showing required 'id' and 'code'.

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?

There is no guidance on when to use this tool versus alternatives. The description offers no context about when to prefer this over 'payments_list_coupons' or how it relates to other coupon operations. No exclusions or alternative conditions are mentioned.

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