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

Goes well beyond the annotations by disclosing that nothing is charged, that the session is held only until the quote expires, and that the cancellation policy must be shown to the traveler. The 'WRITE' marker matches readOnlyHint=false and destructiveHint=false, so there is no contradiction.

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-loaded with 'WRITE.' then purpose, then returned data, then the safety note; every sentence carries distinct information and there is no padding.

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 enumerates the meaningful return values (authoritative total, cancellation policy, amenities, payment term, evidence). The main gap is the lack of guidance on property_id/adults/children, though these are largely self-evident.

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 only 40%, so the description must compensate. It adequately explains stay_id's provenance and the schema itself covers booker's behavior ('incomplete' without it), but property_id, adults and children receive no meaning in either place.

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 ('Opens a UCP lodging booking session from a quoted offer') and ties the key input to its producing sibling (get_availability_quote). Differentiation from create_booking and complete_booking_session is only implied by the session-vs-booking wording, not called out by name.

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 prerequisite is explicit: the session is built from a quote, and stay_id must come from get_availability_quote. It does not explicitly say when to choose this over create_booking or complete_booking_session, so context is clear but exclusions are absent.

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