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

With no annotations, the description fully discloses key behaviors: validation, recording, auto-apply discount, idempotency, and zero cost. It also notes the requirement for npub. No contradictions or omissions.

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 brief (5 sentences) with a clear front-loaded purpose. Every sentence adds value, covering action, validation, effects, cost, and idempotency. No redundant or vague statements.

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 coupon redemption tool with an output schema, the description covers all essential aspects: how it works, prerequisites, side effects (auto-apply discount), and idempotency. It is sufficient for an agent to use correctly without additional information.

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 description explains 'code' as the operator-shared coupon name and 'npub' as required proof. The optional dpop_token is not described, but it has a default and is less critical. Given 0% schema coverage, the description adds meaningful context.

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 that the tool claims a coupon by code, with specific actions: lookup, validation, and recording. It distinguishes from sibling coupon tools (mint, delete, update, list) by focusing on redemption and auto-application of discounts.

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?

It explicitly states when to use (claim a coupon) and prerequisites (npub). It mentions idempotency and the free nature. However, it does not explicitly contrast with alternatives or state when not to use, slightly reducing clarity.

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