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

Annotations only flag destructiveHint=true; the description adds that the change is reversible, how to reverse it, and what is returned ('the updated booking'). That is meaningful context beyond the annotation, though it doesn't cover side effects like notifications sent to the booker.

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?

One tight sentence chain with the mutation warning front-loaded, followed by implementation, safety, reversal path, and return value. No filler.

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 one-parameter mutation with no output schema, the description covers effect, mechanism, reversibility, alternative, and return value. Nothing an agent needs to call it 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?

Only one parameter and schema coverage is 100% — the schema already documents bookingId as a required path id. The description adds no format, example, or lookup guidance beyond that, so this sits at the baseline for fully-covered schemas.

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 ('cancels a booking') and immediately identifies the underlying operation (PATCH /v1/bookings/{bookingId} with { cancelled: true }). The contrast with deleting makes it distinguishable from update_booking and any delete sibling.

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?

Explicitly frames this as the safer alternative to deleting and names the reversal path (youcanbookme_update_booking with cancelled=false). What's slightly left implicit is when an agent should pick this over calling update_booking with cancelled=true directly, since the description admits they are the same operation.

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