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

Annotations only say destructive/non-idempotent/open-world; the description adds genuinely new behavior: the buyer is notified, the outgoing message is labelled as AI-sent on the seller's behalf, and the required OAuth scope `enquiries:respond`. It stops short of saying duplicate sends produce duplicate notifications, but the side-effect profile is otherwise well disclosed.

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 action, followed by scope, side effects, auth, and a single illustrative example. Every sentence carries information an agent would otherwise have to guess.

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 two-parameter mutation with an output schema, the description covers auth, audience, notification side effect, and AI disclosure. Minor gaps remain around error handling for an invalid or foreign enquiryId.

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%, so both parameters are already documented. The description reinforces that the enquiryId must belong to the seller and the example implies the answer is natural seller-voiced text, but adds no format, length, or validation detail beyond the schema.

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 and resource ('Send the seller's reply to a buyer who messaged about one of the authenticated user's listings') and pins the scope to the seller's own enquiries, which separates it cleanly from make_enquiry and get_my_enquiries.

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?

Gives a clear context of use plus a realistic example utterance that shows the intended caller flow (find latest enquiry, then reply). It does not explicitly name get_my_enquiries as the way to obtain the enquiryId, so routing is implied rather than stated.

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