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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, and the description is consistent with that. Beyond the annotations it adds genuinely useful behavior: output units (in for snowfall, F for temperature), the 3-hourly vs daily granularity, and the presence of canonicalUrl and observedAt fields that signal data provenance and freshness.

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?

Front-loaded with the core purpose in one sentence, then the disambiguation, then the unit/return caveat — a sensible ordering with little waste. The final clause ('Read-only results use in for snowfall, F for temperature, and include canonicalUrl and observedAt') is dense and telegraphic, slightly harder to parse than necessary.

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 must carry return-value information, and it does name the key fields and units. It leaves some gaps for a forecast tool — the daily-vs-3-hourly payload shape and what 'multi-model' means in the title are not described — but the essentials for correct invocation are present.

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 description coverage is 100%, so the schema already explains the resort identifier forms, the days range, and the lang enum. The description adds no parameter-level meaning beyond that (e.g., it never clarifies that resort accepts a name, slug, or search_resorts ID), so the baseline of 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 and resource ('Get ... forecast numbers'), the exact scope (15-day daily and 3-hourly, one ski resort) and the variables covered (snowfall, rain, temperature, wind). It explicitly contrasts with the sibling get_forecast_confidence, so an agent can differentiate without opening either 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 selecting rule: use this for forecast numbers for one resort, use get_forecast_confidence for multi-model spread and horizon uncertainty. It does not address other plausible siblings such as get_conditions, find_powder, or compare_resorts, so the routing guidance is good but not exhaustive.

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