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

Annotations already cover readOnly, idempotent, openWorld, and non-destructive, so the safety profile is known. The description adds genuinely new behavior: the slot is revalidated at call time and can come back unavailable with a reason, and the user completes login/booking/payment on the provider site while Zarvo never reserves inventory. That is exactly the kind of external-side-effect context an agent needs.

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, front-loaded with the trigger and outcome statuses, and the scope limitation stated last. Every sentence carries information an agent needs.

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?

The output schema and annotations already cover return shape and safety, so the description rightly focuses on workflow and the unavailable/available outcome. The one real gap is that neither parameters nor their constraints are explained anywhere.

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 description coverage is 0%, and the description says nothing about slot_id or number_of_players, so the description fails to compensate. The number_of_players constraint (min 1, default 4, max 4) is especially opaque without explanation.

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 action (revalidate a provider slot, return handoff URL and current price) with clear scope: Zarvo does not reserve inventory or complete checkout. It doesn't explicitly differentiate from the sibling recheck_slot, which sounds like a near-identical operation.

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?

"Use this directly after the user chooses a slot" gives a clear trigger condition, and the description implies this is the final step before handing off to the provider. It stops short of naming when NOT to use it, e.g. versus recheck_slot or get_availability.

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