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

Annotations only cover the safety/idempotency profile; the description goes well beyond by disclosing the dwell-time clock lifecycle, idempotent repeat behavior (keeps first arrival time), the appointment.arrived webhook, the absence of a carrier email, the return payload, and the required appointments:receive scope with role prerequisite.

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?

Dense but front-loaded: the core action and dwell-clock effect come first, followed by undo, alternatives, side effects, and auth. Every sentence carries distinct information, though the single-paragraph density is slightly heavier than necessary.

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?

No output schema exists, yet the description explains the return value (updated appointment with checkedInAt as arrival time). Combined with webhook, auth scope, and sibling routing, an agent has everything needed to 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 100%, so the baseline is 3, but the description adds real semantics beyond it: arrived:false undoes a mistaken arrival and repeated calls preserve the first arrival time. The appointmentId parameter is left to the schema, which is fine at full coverage.

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 ('Record that a truck has physically arrived at the dock') and immediately differentiates it from two siblings, check_in_appointment and set_appointment_status COMPLETED. An agent can select it 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?

Gives explicit when-to-use ('truck has physically arrived'), when-not ('Not the same as check_in_appointment, which records the driver's own on-track or running-late update'), and the correct alternative for the departure event (set_appointment_status COMPLETED). Undo behavior is also spelled out via arrived: false.

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