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

Annotations already declare readOnly, idempotent, non-destructive and open-world. The description adds genuinely new behavior: results come from a 'fresh calendar snapshot', possible outcomes are available_in_snapshot / blocked / unknown, and it explicitly never reserves gear. It stops short of describing caching, rate limits, or staleness windows.

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 short sentences, front-loaded with the core action before the return behavior and the non-reservation caveat. Slightly terse in the middle clause ('blocked or unknown' is compressed), but no sentence is wasted.

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 correctly carries the return-value burden by naming the result states. Combined with full schema coverage and rich annotations, an agent has enough to invoke it correctly; only edge cases like error behavior on an invalid slug are unaddressed.

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 baseline is 3, but the description adds semantics the schema does not: omitting from_date/to_date changes the tool into a blocked-date listing rather than a range check. That conditional behavior is real value beyond the parameter definitions.

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 ('Check both pickup and return dates against a fresh calendar snapshot') and clarifies the tool's scope with 'never reserves gear', which separates it from booking siblings like start_booking. An agent can distinguish this from get_rental_quote or start_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?

Gives a clear conditional mode: with dates it checks a range, without dates it lists known blocked dates. It does not, however, name an alternative tool or state when to prefer it over siblings (e.g., start_booking), so the routing guidance is contextual rather than explicit.

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