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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and closed-world, so safety is covered; the description still adds real substance: result filtering semantics (only resorts scheduled or confirmed to open that date), the holiday-mode result shape ('on or before the holiday', each with its record, sorted by rate), and that holiday dates are computed. It stops short of edge-case behaviour such as what an empty result means, which keeps it below a 5.

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 scope and the negative case, then alternatives, then the holiday mode — a sensible ordering with no filler sentences. It is long and parenthetical-heavy, with several quoted example questions that could be trimmed, which is the only thing keeping it from a 5.

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 an output schema present and 100% parameter coverage, the description need not explain return values, and it still covers scope, exclusions, sibling routing, and the two operating modes. Nothing an agent needs in order to select or invoke this tool 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 baseline is 3; the description goes further by explaining the `date` vs `holiday` precedence and the `year` semantics in prose, plus the holiday date computation. It does not add anything for region/country/hemisphere beyond what the schema already documents.

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?

The description states a precise verb+resource scope: resorts whose season opening date equals a specific day, with concrete example questions. It explicitly excludes the neighbouring interpretation ('NOT all currently-open resorts') and names the sibling tools it should not be confused with, so an agent can separate it from get_southern_hemisphere_report, get_insights, and ask_snowdata without opening any 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?

Unusually complete routing: it names when to prefer this tool over get_southern_hemisphere_report, and gives two explicit when-not cases mapped to concrete alternatives (get_insights with category=season_calendar for ranked retrospectives, ask_snowdata for historical norms). It also states the in-tool mode switch (pass `holiday` instead of `date`) for US holiday questions.

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