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

The destructiveHint annotation flags this as a mutating operation, and the description adds value beyond it: it discloses the returned attendance id, the reversal path, and the underlying TeamUp endpoint. It still doesn't say what a failed/duplicate booking does or whether a membership gets consumed/charged explicitly, but the coverage is solid.

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?

A single tight sentence covering purpose, options, return value, undo tool, and endpoint — front-loaded and waste-free. The endpoint tail is slightly extraneous for an agent but harmless.

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 4-param mutation tool with no output schema, the description covers what matters: what it does, the two booking modes, and the returned id. Prerequisite/auth conditions and duplicate-booking behavior are the only meaningful gaps.

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 all four parameters already carry descriptions including the 'omit to let TeamUp choose' behavior for customer_membership. The description only restates the comped/membership semantics rather than adding syntax or constraints beyond the schema, so baseline 3 applies.

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+resource ('Register a customer for a class or appointment') and clarifies the two booking modes (membership-backed vs comped). It also names the undo counterpart, goteamup_unregister_customer_from_event, so an agent can tell the two apart without opening schemas.

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?

Explains what the optional paths mean (use a specific membership, or book comped/free) and points to the undo tool. It does not, however, state prerequisites (e.g., that the customer must already exist or the event must be bookable) or when to prefer this over sibling listing/attendance tools.

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