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

Annotations already declare the mutation profile (readOnlyHint=false, destructiveHint=true, idempotentHint=true), so the description adds value by disclosing what carries over: client, stylist, services and length persist and reminders move with the appointment. That reminder migration is a real side effect not visible in any structured field. It does not, however, surface the optimistic-concurrency refusal behavior, which is the most consequential runtime trait.

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 short sentences, zero filler, and the triggering condition is front-loaded before the behavioral detail and the exclusion. Every clause carries new information.

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?

An output schema exists, so return shape need not be spelled out, and the annotations carry the safety profile; the description correctly focuses on intent and carry-over semantics. The only meaningful gap is the conflict/staleness refusal implied by expectedLastEditTime and the mild tension with durationMinutes.

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 the schema already explains appointmentId, startTime, durationMinutes and expectedLastEditTime thoroughly, and the baseline of 3 applies. The description adds nothing parameter-specific, and "its ... length stay[s] the same" sits slightly at odds with the optional durationMinutes field that can change the length, leaving an agent to reconcile the two.

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 an appointment to another day or time" gives a specific verb and resource, and the closing clause separates it from the cancel path. An agent can tell this apart from cancel_appointment (and from book_appointment, a new booking rather than a move) 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?

"Use this when someone asks to move an appointment" states the triggering intent explicitly, and "Not for cancelling an appointment" gives an explicit exclusion that routes the agent to the sibling tool. Both the when and the when-not are present in a single sentence pair.

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