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

With no annotations provided, the description fully discloses behavior: it validates the coupon window and cap, records per-patron redemption, auto-applies discount on subsequent calls, requires npub proof, and is idempotent. This is comprehensive.

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 a single, well-structured paragraph that starts with the action and provides necessary details (validation, idempotency, cost) without unnecessary words. Every sentence adds value.

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 (redemption with side effects and auto-application of discount), the description covers the essential behavioral aspects. The existence of an output schema excuses missing return value details. No gaps identified.

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 coupon name and 'npub' as required for proof. The dpop_token parameter defaults to '' and is not explained, but overall the key parameters are well-described despite 0% schema coverage, exceeding the baseline for low coverage.

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 'Claim a coupon by its name' and outlines the process of looking up a coupon by code, validating constraints, and recording a redemption. It distinguishes from siblings like mint_coupon (creation), list_coupons (listing), etc., and mentions idempotency.

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?

The description implies usage context: it is free, requires npub, and subsequent paid calls auto-apply discount. It does not explicitly list when not to use but contrasts well with sibling tools, making the appropriate use case clear.

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