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

Annotations already declare the write, non-idempotent, open-world, destructive profile, so the description's real contribution is the two-step flow: this call only holds a spot and hands back a checkout link where payment or a pack/membership is applied. That is valuable context an agent would otherwise assume away, but it omits hold expiry, whether repeat calls create duplicate holds, and what happens if the link isn't used.

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 tight sentences with the core action and return value front-loaded, followed by the prerequisites. Nothing is repeated and no filler appears.

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?

With no output schema, the description correctly explains the return value (a checkout link) and the downstream confirmation step, which is the key thing an agent needs to relay. Remaining gaps — hold duration, failure modes, and sibling selection versus book_session — are minor but real for a booking mutation.

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 is already documented, and the description mostly restates that service_id/event_id come from get_class_schedule and that first name and email are required. It adds no format, validation, or optional-field guidance (phone, last_name) 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?

"Holds a spot in a live NOGA class for a person and returns a nogamovement.com checkout link" states a specific verb and resource, and the "live class" framing implicitly separates it from the 1:1 book_session sibling. It never names book_session or explains which to pick, so an agent must infer the distinction.

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 a concrete prerequisite chain: the service_id and event_id must come from get_class_schedule, plus the person's first name and email. It provides clear context for when the call is valid but offers no exclusions (e.g., when to use book_session instead) and no note on retry/repeat behavior.

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