get_coupon_usage

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, but the description goes well beyond them: it states auth is injected server-side, rate limiting/retry behavior, pagination specifics (50 per page, sorted order), and detailed non-2xx error semantics. No contradiction 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 long but well-labeled and information-dense, with the read-only and endpoint context front-loaded. Minor redundancy exists between the opening line and the second sentence, but every section earns its place given the pagination, auth, and error behavior that must be conveyed.

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 covers the return envelope, error handling, pagination, ordering, and safety profile. It does not enumerate the exact JSON fields of a coupon usage record, but it conveys enough for selection and invocation.

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 baseline is 3, but the description adds meaningful operational meaning: 'results are paged — walk them with page', the 50-per-page limit, and ordering by most recently created payment. This helps the agent use the page parameter correctly beyond the schema's terse description.

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 ('Get coupon usage') and unpacks it with concrete details: coupon usage details plus associated payments, sorted and paginated. The 'Related Promotions tools' list and read-only marker also help distinguish it from sibling promotion tools.

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 says it is safe to call speculatively for lookups and reporting, and warns against using it for changes, pointing to the matching write tool. It lists related Promotions tools but does not precisely contrast this tool against the closest read sibling, get_promotions_coupons.

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