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

With no output schema, the description usefully discloses return values (available room and rate, total price in euro cents, and a finalization URL) plus the prepaid-only, non-refundable payment policy and the failure mode when the hotel is full/closed. This goes well beyond the readOnly/openWorld annotations, though session lifetime and idempotency are not covered.

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?

Four front-loaded sentences in a logical order: purpose, return values, booking constraint, error behavior. No filler, though it is slightly longer than strictly necessary.

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?

Given no output schema, the description adequately explains what comes back (room, rate, price, URL) and the key constraint and error case. It is broadly complete for a session-creation tool, with only gaps around multi-stay handling and the handoff to get_booking_session/update_booking_session.

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 only ~50% and the payload is deeply nested. The description adds meaning for 'dates et occupation' (mapping to stay_dates/occupancy) and the prepaid constraint tied to rate_plan, but says nothing about accommodation_type, property, or the meta/booker objects, so it only partially compensates for the coverage gap.

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?

Names a concrete verb ('Ouvre une session de réservation'), a named resource (session at Hôtel-Rooftop Les Voiles, Toulon/Mourillon) and scope (dates + occupancy). It is unambiguous what the tool does, but it never distinguishes itself from siblings like create_rooftop_reservation or get_booking_session.

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?

Usage is implied rather than stated: the description notes only PREPAID rates can be booked by an agent, which is a genuine eligibility constraint. However there is no explicit when-to-use / when-not-to-use guidance and no routing to alternative siblings (e.g. for non-prepaid or rooftop bookings).

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