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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint=false, so safety and idempotency are covered. The description adds genuinely useful behavior beyond that: the snow figure is explicitly a 'rough estimate derived from the forecast wording' (an accuracy caveat) and the US-only coverage with an available=false sentinel rather than an error.

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 with no filler; the core purpose and output contents lead, and the geographic limitation is placed immediately after so it is read before the call is made.

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?

An output schema exists, so return values need not be explained, and the description covers the key caveats (derived snow estimate, US-only coverage, available=false). The only omission is guidance on sibling selection, which is a minor gap for a single-parameter read 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?

Schema description coverage is 100% and the single slug parameter is fully documented there, including the kebab-case format and the pointer to search_resorts. The description adds nothing about the parameter, which is the expected baseline when the schema already does the work.

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 ('Five-day National Weather Service forecast') plus the exact payload fields (high/low, text forecast, precipitation chance, wind) and an added derived snow estimate. An agent can distinguish this from get_resort_conditions and get_snow_history 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?

Gives a clear negative condition — NWS covers US resorts only, so Canadian and Andes resorts return available=false — which prevents wasted calls and misinterpretation of empty results. It does not, however, name when to prefer this over siblings like get_resort_conditions or find_powder, so it stops short of full alternative routing.

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