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

No annotations are provided, so the description carries full burden. It clearly discloses the non-final booking behavior (returns checkout URL, not booked until payment), server-side slot re-validation, and lack of email verification. All critical behavioral traits are 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?

The description is longer (85 words) but front-loaded with the most critical warning in ALL CAPS. Every sentence serves a purpose: explaining the payment flow, precondition, return value, and email verification status. Could be slightly shortened, but no filler.

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 annotations, no output schema, 6 parameters (with nested object), the description fully covers return value ('checkout URL'), preconditions (call get_availability), side effects (nothing booked until payment), and behavioral caveats (slot re-validation, email not verified). The tool's complexity demands this level of detail.

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%, but the description adds valuable context beyond parameter names: e.g., startDate/endDate should be 'exactly as returned by get_availability', resourceId is 'from the slot', contact fields are 'required by the venue to confirm or reschedule'. This aids correct usage.

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?

The description uses a specific verb 'book an appointment slot at a venue' and clearly identifies the resource ('Wix Bookings'). It distinguishes itself from sibling tools like create_checkout (payment) and get_availability (precondition) by stating the booking is not final until payment and that get_availability should be called first.

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?

Provides explicit guidance: 'Call get_availability immediately before this – the slot is re-validated server-side and a taken slot is rejected.' Also instructs 'Tell the user they must open the link' and notes email is not verified here. This covers when to use and what to do next.

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