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

Annotations already declare destructiveHint=true, idempotentHint=true and openWorldHint=true; the description goes beyond them by stating which fields are preserved (patient, providers, procedures, length), that reminders migrate with the appointment, and that the result includes both new and previous start. It does not discuss the concurrency-refusal behaviour or permission requirements, which the schema partly covers via expectedLastEditTime.

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?

The usage trigger is front-loaded in the first clause, and the remaining clauses pack preservation rules, reminder behaviour and return shape into one sentence with no filler or repetition.

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 destructive mutation tool this covers what an agent needs: when to call it, what is preserved, what happens to reminders, and what comes back. Since an output schema exists, the return description is a bonus rather than a requirement; only failure modes and permissions are left implicit.

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%, so every parameter is already documented in the schema, including the ISO 8601/UTC-offset format and the expectedLastEditTime refusal rule. The description reinforces one parameter's semantics (length is kept unless a new length is given) but adds no syntax or constraint detail beyond that baseline.

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?

"Move a patient's appointment to another day or time" gives a specific verb (move) plus resource (patient appointment) with the scope of change stated. It distinguishes itself from cancellation ("Not for cancelling") but does not explicitly contrast with book_appointment, the other sibling that creates rather than moves an appointment.

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?

The opening clause gives an explicit trigger (someone asks to move an appointment to another day or time) and closes with a clear exclusion ("Not for cancelling"), which routes the agent away from cancel_appointment. No guidance is given on the create-vs-move boundary against book_appointment, so it stops short of full alternative routing.

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