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

Annotations only declare the mutation/safety profile (readOnly false, destructive false, idempotent false), and the description layers on substantial behavioral context: conflict, capacity and rebooking-policy validation, actor permission and outlet access enforcement, calendar sync, and an updated-booking return. That tells the agent what can fail and why, which the annotations never do.

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?

Two sentences, no filler, and the core action is front-loaded before the exclusion and the behavioral checks. Every clause carries distinct information — scope, restriction, then validation/side effects.

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 an 8-parameter mutation with an output schema and full schema coverage, the description covers scope, exclusions, validation, permissions and the return payload, which is nearly everything an agent needs. The remaining gap is update semantics — whether unspecified fields keep their values — which matters for a partial-update reschedule call.

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 every parameter already carries its own description and the baseline is 3. The description only restates the changeable dimensions already visible in the schema; it adds no new constraint such as partial-update semantics (whether omitted fields are preserved) or interaction between startTime/endTime and scheduleId.

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 ('Move or reassign') against a specific resource ('a single-service booking') and enumerates the dimensions that can change (date, time, staff, resource, schedule slot). It also scopes itself against non-single-service bookings, so an agent can separate it from cancel_booking and create_booking without opening a 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 a clear use case plus an explicit exclusion: multi-service appointments must go to the merchant dashboard. That is real routing guidance. It does not name a sibling tool for the excluded case or cover when to cancel-and-recreate instead of reschedule, keeping it out of the 5 tier.

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