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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the agent knows this is a safe local read. The description adds that results include resort counts, which is useful output context, but says nothing about ordering, pagination, or how large the tag set is.

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?

A single sentence that front-loads the verb and resource and packs in the grouping semantics and the included resort counts with zero filler.

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 carries the burden of describing what comes back, and it does so at a high level (region tags plus resort counts). The remaining thinness — no ordering or size expectations — is minor for such a simple listing tool.

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 tool takes no parameters, so there is nothing for the description to disambiguate; per the rubric a parameterless tool baselines at 4. No parameter-level gaps exist.

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 (list) and resource (region tags), and even clarifies what a 'region' is here — tags resorts are grouped by, such as states, countries, ranges — plus that each carries a resort count. It is distinguishable from ski_get_region_summary by being an enumeration rather than a single-region detail call, though it never names that sibling explicitly.

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 enumeration framing implies the use case (discovering valid region tags, likely for filtering in ski_search_resorts), but there is no explicit when-to-use statement or comparison to ski_get_region_summary. For a zero-argument list endpoint the intended usage is largely self-evident, so implied guidance is acceptable.

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