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

With no annotations, the description carries the full burden and discloses very little: no units (metric/imperial), no timezone semantics for 'hourly', no behavior on an invalid or unknown site code, and no note on response shape beyond it being a forecast. It only adds a language constraint.

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 compact sentences with the resource statement front-loaded and no filler. Terseness is appropriate here; the brevity is a limitation of content, not of structure.

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?

A 3-parameter tool with no annotations and no output schema requires the description to explain units, time horizon behavior, and language fallback. Instead it covers only the language values, leaving the agent to guess at the rest.

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 0%, so all three parameters lack documentation. The description explains site_code (location identifier) and constrains lang to en or fr, but the 'hours' parameter — defaulting to 24 — is never mentioned at all, leaving a third of the surface undocumented.

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 combination: returns an hourly forecast for a location identified by site code. Among siblings, the 'hourly' qualifier implicitly separates it from get_daily_forecast and get_current_conditions, though it never names them 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?

No guidance on when to pick this over get_daily_forecast, get_current_conditions, or get_air_quality. It also doesn't say whether a prior search_locations call is needed to obtain a valid site_code.

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