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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds real value beyond them: expiry dates are in UTC, notes are private and never seen by buyers, and an API-key requirement is stated.

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?

Purpose and returned fields are front-loaded, and the extra details (UTC, private notes, auth) are compact. A sentence on notes/privacy is slightly tangential but earns its place as buyer-facing context.

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 read-only list tool with annotations covering safety and a fully documented input schema, the description supplies the returned fields and key behavioral notes. It does not explain pagination behavior via the cursor, which is the only meaningful gap given the absence of an output schema.

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% and both parameters (limit, cursor) are documented in the schema. The description adds nothing about pagination or the limit/cursor semantics, so the baseline of 3 is appropriate.

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 (list) and resource (coupons) and enumerates the returned fields (discount, scope, uses, usage limit, expiry). This clearly distinguishes it from the sibling payhip_create_coupon, but it never names the alternative explicitly.

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 intent to retrieve coupons is implied but there is no explicit when-to-use versus when-not, nor any reference to the sibling create_coupon. The auth prerequisite ('Needs the user's Cotlet API key with access to this app') is useful context but is not usage guidance.

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