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

Adds useful behavioral context beyond annotations: destructive/side-effect warning about penalty triggers from late cancel, plus note that the response indicates whether it counted as late. Annotations already mark destructiveHint=true, but description enriches with consequence awareness.

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 tight sentences: purpose, key parameter caveat, return value hint, API path. Front-loaded. No waste.

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 3-param mutation with annotations covering destructiveness and full schema coverage, this is complete. Minor gap: no output schema, but description notes the response reports late-cancel status, so the agent knows what to check.

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 parameters are already documented. The description echoes and contextualizes is_late_cancel with consequence framing, but adds no syntax or format detail. 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?

Clear specific verb+resource: 'Cancel a customer's booking for a class or appointment.' Distinguishes from sibling goteamup_register_customer_for_event by directly opposing it, and the API endpoint reference (POST /events/{id}/unregister) anchors it.

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?

Provides a clear conditional instruction for is_late_cancel ('leave it unset unless asked'). No explicit when-not to use the tool itself or alternatives, but context is strong enough to route correctly.

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