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

Annotations already declare destructive=true and idempotent=true, but the description goes well beyond them: irreversibility ('can't be restored'), double-cancel being a no-op, the conflict on COMPLETED/NO_SHOW, and the concrete side effects (carrier cancellation email, stops pending reminders, appointment.cancelled webhook). It also discloses the required scope and role, which annotations do not carry.

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, the state transition, and the irreversibility warning before routing guidance and side effects. It is dense — several clauses per sentence — but nearly every clause carries distinct operational information, so little is wasted.

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 single-parameter mutation with no output schema, the description covers everything an agent needs: preconditions, finality, idempotency behavior, sibling routing, side effects, return value, and authorization scope. No meaningful gap remains.

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 100% and there is a single parameter, so the schema already fully documents appointmentId including its sources. The description adds no syntax or format detail beyond that, making the baseline 3 correct.

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 ('call off a CONFIRMED appointment') and immediately scopes it with the state it operates on and the resulting state (CANCELLED, door time freed). It explicitly names the sibling tools it is not (reject_appointment, reschedule_appointment, set_appointment_status NO_SHOW), 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?

Gives explicit when-to-use and when-not-to-use: decline a PENDING request via reject_appointment, move time via reschedule_appointment, no-show via set_appointment_status NO_SHOW. It also states the precondition (must be CONFIRMED; COMPLETED/NO_SHOW conflict) and the user-confirmation requirement before acting.

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