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

Annotations already declare readOnly and openWorld, but the description adds real behavioral context: data is operator-reported, results are sorted by share of lifts open, and missing counts carry a distinguishing reason (listed none vs. unreadable). That last point is genuinely useful because it tells the agent not to treat a blank as zero. No auth or rate-limit detail, which is a minor gap.

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 led by the primary purpose, then the data-quality caveat. Every clause carries information the agent needs and there is no filler or repetition of the tool name.

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?

With no output schema, the description usefully describes the return shape (lift counts, sorted by share open) and how to interpret absent values. It is nearly complete for this tool; only the unavailable-count reason wording and error behavior for invalid resort names are unspecified.

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% and the single parameter is fully described in the schema as 'Resort ids or names' with min/max items. The description's 'up to 10 resorts' largely restates maxItems without adding accepted format or disambiguation rules for names vs. ids, so 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?

States a specific verb (compare) and resource (open-lift counts) plus the scope limit of 10 resorts and the sort order, so the agent knows exactly what comes back. It never names the sibling it complements (e.g. ski_get_resort_status for a single resort), so differentiation is implied rather than stated.

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?

Multi-resort comparison is clearly implied by 'side-by-side ... for up to 10 resorts', which tells the agent to reach for this tool when several resorts are in play. However, there is no explicit when-not guidance or named alternative for single-resort lookups, so the routing decision is left to inference.

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