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

Annotations already declare readOnlyHint=true and idempotentHint=true, so safety is covered and the trailing 'Read-only' adds little. The description does add real behavioral context, however: the 24-hour booking rule, the Jamaica-time requirement, and the fact that both leg results and earliest bookable times are returned.

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?

Front-loads the purpose, then the business rule, then parameter guidance, then return value. Dense but every sentence carries information; the closing 'Read-only' is the only element that duplicates the annotations.

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 usefully explains the return (bookable per leg plus earliest bookable time) and covers all three parameters, including their either/or relationship. The only minor gap is behavior when zero arguments are supplied, since required parameters are 0.

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 already 100%, so the baseline is 3, but the description adds genuine meaning: departure_at and departure_flight_at are presented as alternatives for the return leg, and it explains that the pickup is derived when departure_flight_at is supplied. That mutual-exclusion logic is not in the schema.

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 and resource ('Check whether a pickup can be booked online'), which clearly separates it from siblings like start_transfer_booking and get_transfer_quote. It does not name those siblings explicitly, but the pre-booking validation intent is unambiguous.

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 24-hour notice rule and the destination-based (Jamaica time) framing imply this is a pre-booking eligibility check, but the description never explicitly says when to call it versus start_transfer_booking or get_transfer_quote. Usage is inferred rather than stated.

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