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

Annotations only declare destructive/not-read-only/idempotent; the description adds the consequences an agent cannot infer: the customer may be notified, the event is removed from connected calendars, and the appointment cannot be restored through the API. That is exactly the extra context annotations don't carry. The idempotentHint does not conflict with 'irreversible' — cancelling twice is still safe.

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 tightly packed sentences, with the risk classification front-loaded before the operational detail and the call condition. The trailing endpoint line is short and adds traceability rather than noise.

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 destructive mutation with no output schema, this covers the risk profile, the side effects, the irreversibility, and the authorization condition for calling it. Nothing an agent needs in order to act correctly is missing.

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, including the provenance hint for appointment_id. The description adds no parameter-level meaning beyond confirming that the id is the DELETE path segment. Baseline 3 is appropriate.

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 ('delete (cancel) an appointment') up front, and the WRITE/IRREVERSIBLE prefix distinguishes it immediately from read siblings like bookafy_list_appointments and from bookafy_update_appointment. An agent can select it without opening the 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 an explicit gating condition: 'Only call it when the user explicitly asked to cancel this appointment.' That is a real exclusion rule rather than implied usage. It stops short of naming the alternative for the adjacent case (rescheduling via bookafy_update_appointment), so it is not a 5.

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