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

Annotations only declare the safety profile (read-only, idempotent, closed-world), and the description layers on real domain behavior the agent cannot infer: the same-day cut-off shifting the earliest arrival date, the same-rooms-free-on-every-night constraint, and the multi-room splitting rule. This is exactly the beyond-annotation context that prevents wrong conclusions from a 'no' verdict.

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?

Three sentences, front-loaded with the user-facing question, then the return payload, then the rules and the sibling preference. No sentence is filler; each one changes how the agent would call the tool.

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?

Output schema exists, so return-value enumeration is not required, yet the description still summarizes the verdict shape and warns about the multi-room case. Combined with the full parameter schema and safety annotations, nothing an agent needs to invoke this correctly is missing.

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 the baseline is 3, and the description adds meaning by framing the inputs as a party size plus a stay length and by disclosing the earliest-arrival rule that governs check_in. It does not add syntax or default-behavior detail beyond the schema, so it sits modestly above baseline rather than at the top.

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?

Opens with the concrete question the tool answers ('can a party of N stay from DATE for N nights?') and names the exact return payload: verdict, refusal reason, room combinations, booking URL. This clearly separates it from the raw-calendar sibling without requiring schema inspection.

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?

'Prefer this over reading the raw calendar' explicitly routes the agent away from get_availability_calendar, and the note that an oversized party is NOT a refusal prevents a common misuse. No exclusions for the other siblings (get_hotel_info, list_public_events) are needed since they serve different intents, but the alternative is referenced by concept rather than tool name.

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