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

With no annotations provided, the description carries the full burden and does so thoroughly. It discloses validation behavior (window and total cap), side effects (records a redemption row, auto-applies discount until uses_per_patron is exhausted), cost (free), authentication requirement (proof of npub), and idempotency.

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 compact and front-loaded, with the core action in the first sentence and each subsequent sentence adding distinct value: mechanics, downstream effect, cost, auth, and idempotency. There is no filler or repetition.

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 three-parameter tool with an output schema and no annotations, the description covers purpose, behavior, side effects, cost, auth, and idempotency well. It is slightly incomplete on error/edge-case behavior and on how dpop_token factors into the proof requirement, but an agent can generally invoke it correctly.

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 usefully explains that code is the operator-shared coupon code and that npub requires proof, but it never mentions the dpop_token parameter or how the proof should be supplied. This leaves a meaningful gap for an agent selecting parameters.

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 opens with a specific verb and resource: 'Claim a coupon by its name (the code the operator shared).' It goes on to explain the coupon lookup, validation, and redemption recording, which clearly separates this from coupon creation, listing, update, and delete siblings.

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 gives clear context for when to call it: a patron claiming an operator-shared coupon, with downstream effects on subsequent paid calls. It also notes the action is free and requires proof of npub, but it does not explicitly name sibling alternatives like mint_coupon or list_coupons or state exclusion conditions.

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