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

readOnlyHint=true already establishes this is a safe read, so the description only needs to add context. It adds the underlying endpoint (GET /businesses/{businessId}/availability/booking-slots) and the word 'free' (filtered to unbooked), but says nothing about pagination, slot granularity, or whether booked/blocked slots are excluded vs. flagged.

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?

Two tight sentences with the primary capability front-loaded, followed by workflow guidance. The trailing API endpoint reference is marginally useful for debugging but is the one element that doesn't strictly earn its place for an agent caller.

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?

There is no output schema, so the description carries the burden of describing the return value. It says 'list free time slots' but not what a slot contains (start/end, resource assignment, capacity), which matters because the output feeds directly into booking creation. Adequate for a read tool, but leaves a real gap for a tool with no output schema.

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 100%, so all five parameters (from, to, service_id, business_id, resource_id) are already documented with formats and defaults. The description only restates that the range is a date range and that resource_id narrows to one staff member; it adds no format or constraint detail beyond the schema. Baseline 3 applies.

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?

Specific verb + resource + scope: 'List free time slots for a service in a date range, optionally for one resource.' An agent immediately knows this is availability lookup rather than booking creation. It does not explicitly contrast with the close sibling reservio_get_booking_days, so day-level vs slot-level granularity must be inferred from the names.

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 before creating a booking' gives a concrete workflow position and implicitly routes to reservio_create_appointment_booking / reservio_create_group_booking. No explicit when-not or alternative-tool guidance (e.g., when to prefer get_booking_days or list_opening_hours) is given.

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