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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the core safety profile is covered. The description adds useful behavioral context beyond annotations by clarifying that this is a non-reserving, read-only availability lookup and that the window is UTC.

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 short sentences with no filler. The core behavior and the non-booking caveat are front-loaded, making the tool easy to scan and understand quickly.

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?

For a simple read-only tool with rich annotations and an output schema, the description covers the essential behavior. It omits where action_id comes from and does not reference related setup tools like list_public_booking_services, but overall the agent has enough to use it correctly.

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?

The description adds some meaning beyond the raw schema: 'one service' clarifies service_id, and 'UTC window' clarifies start/end semantics. However, action_id is not explicitly explained; it is only implied by 'supported clinic widget.' With 0% schema description coverage, more field-level guidance would be expected.

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 clearly states the operation ('Read public availability') and the resource scope ('from a supported clinic widget for one service and UTC window'). It also explicitly differentiates itself from booking tools by noting it does not hold or book a slot.

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 description provides clear context: use this to read public availability for a single service over a specified UTC window. It also rules out holding/booking behavior, but it does not name alternative sibling tools or explicitly state when not to use this tool versus list_xona_booking_slots or hold_xona_booking_slot.

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