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

With no annotations, the description carries the full burden and does well: it discloses validation of the window and total cap, per-patron redemption recording, automatic discount application on later paid calls until uses_per_patron is exhausted, that it is free, requires proof of npub, and is idempotent. It omits what a failed validation (expired/over-cap) returns, but the behavioral profile is otherwise rich.

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?

Front-loaded with the purpose, then mechanics, then cost/idempotency notes. Sentences are compact and mostly earn their place, though a few could be tightened.

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?

An output schema exists, so return values need not be explained. Behavior, cost, auth requirement, and idempotency are all covered; the gaps are the undocumented dpop_token and the absence of failure-mode description.

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 0%, so the description must compensate. It adds meaning for `code` and `npub` (proof required), but leaves `dpop_token` entirely undocumented and gives no format detail for npub.

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+resource ('Claim a coupon') and clarifies the identifier ('by its name, the code the operator shared'), which clearly separates it from mint_coupon, delete_coupon, and list_coupons. However, it never names a sibling explicitly to route the agent between them.

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 context ('the code the operator shared') implies when a patron would call it, but there is no explicit when-to-use/when-not guidance or named alternative. The agent must infer the trigger condition from the phrasing.

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