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

Annotations only mark destructiveHint=true, but the description goes further by stating the mutation effect, the underlying PATCH operation, reversibility, and that it returns the updated booking. This gives the agent accurate expectations beyond the annotation.

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 deliver the mutation warning, purpose, endpoint equivalence, reversibility, and return value with no filler. The key action is front-loaded before implementation details.

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 single-parameter mutation with no output schema, this description covers the effect, mechanism, reversibility, return value, and safety posture. Nothing essential is missing for an agent to select and invoke the tool correctly.

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?

The input schema already fully documents bookingId with 100% coverage, including that it is a required path parameter. The description reinforces the endpoint but does not add new parameter-level meaning, so 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?

The description states a specific verb and resource: 'cancels a booking' on YouCanBookMe data. It also clarifies it is a convenience wrapper for PATCH /v1/bookings/{bookingId} with { cancelled: true }, distinguishing it from both deletion and the broader update_booking tool.

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 description gives clear usage context: it is the safer, reversible alternative to deleting, and explicitly points to 'update_booking cancelled=false' for reactivation. It does not explicitly enumerate when not to use it, but the wrapper explanation and sibling reference provide solid guidance.

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