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 declares 'Read-only' and discloses a non-obvious behavioral nuance — that invite rows are recorded but NOT enforced when invite_only is false. It does not mention auth/permission requirements or result-size limits, which keeps it short of a 5.

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?

Three tight sentences with the return shape front-loaded, then the critical flag caveat, then routing guidance. Every clause earns its place, though the parenthetical status list and the routing sentence make it slightly denser than the minimum needed.

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?

There is no output schema and no annotations, so the description properly takes on the job of describing the return shape (statuses, source, timestamps, invite_only) and safety profile. Only the unexplained app_id parameter and absent auth/limit notes leave a small gap.

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 description coverage is 0% and neither parameter is described in the schema, so the description must compensate. It implies that 'code' identifies the coupon being inspected, but never names or explains 'app_id', leaving one of two required parameters unclarified.

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 uses a specific verb+resource ('List who a coupon was offered to') and enumerates the returned fields (per-address status, invite source, timestamps, invite_only flag). It also explicitly distinguishes itself from list_coupons, invite_to_coupon, and revoke_coupon_invite, so an agent can route correctly without opening any schema.

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 final sentence names three sibling tools and states what each is for instead, giving explicit when-to-use and when-not-to-use guidance. It also instructs the agent to read the invite_only flag FIRST and explains why that ordering matters.

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