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

Annotations already cover readOnly/idempotent/non-destructive, so repeating 'Read-only' adds little; the real value is beyond the structured fields — the Asia/Taipei timezone for returned slots, the fact that remaining capacity is included, and the instruction to pass the slot value verbatim into request_booking (implying it is an opaque token). It does not say what an empty result looks like, but the behavioral profile is solid.

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 zero filler; scope, timezone, and capacity come first, then the downstream handoff. Every clause earns its place.

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 read-only tool with rich annotations, complete schema coverage, and no output schema, the description covers the essentials: horizon, timezone, capacity, and how to consume the result. The only gap is the shape of the response when no slots exist, which an agent may need to handle.

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%, so all four parameters including the 1–14 day bound and id derivation are already documented. The description reinforces 'one service' (single service_id) and the day window, but adds no format or syntax detail beyond the schema. Baseline 3 applies when the schema does the heavy lifting.

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 ('List open time slots'), scopes it to one service, a bounded horizon (1–14 days), and adds timezone plus remaining capacity. An agent can distinguish this read-side availability lookup from the write-side siblings like request_booking or modify_booking without opening the schema.

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?

Explicitly routes the agent forward: 'Use the returned slot value as-is in request_booking' is a concrete when-to-use handoff, and 'Read-only' signals this is not a booking action. It stops short of naming when NOT to call it (e.g., to check an existing reservation, use get_booking_status), so no exclusions are stated.

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