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

With no annotations, the description carries the full burden, and it does disclose the read-only safety profile ('cannot create, edit, or delete coupons'), which is the key behavioral trait. It omits pagination behavior and what the default 50-item limit means in practice, leaving meaningful gaps for a no-annotation tool.

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?

Two tightly packed sentences, front-loaded with the resource and its return fields, followed by scope options and the read-only guarantee. No filler and every clause carries information.

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?

With no output schema, the enumerated return fields are a valuable substitute, and scope/safety are covered. The only shortfall is the undocumented limit parameter and pagination behavior, which keeps it just under fully complete.

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%, so the description must compensate. It adds genuine meaning for app_id (scoping) and active_only ('not expired, not maxed out'), which the bare schema does not convey, but the limit parameter and its 50 default are never explained, so compensation is only partial.

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 (discount coupons), then enumerates the returned fields (code, percent off, expiry, max uses, use count, tier applicability), which pins the purpose down precisely. It does not explicitly distinguish itself from the similar sibling list_coupon_invites, so it stops short of a 5.

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?

It gives real usage context — optional scoping by app_id and optional restriction to active coupons — but never states when to prefer this over list_coupon_invites or when filtering is required. Usage is implied rather than prescribed, with no alternatives or exclusions named.

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