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

No annotations are provided, so the description carries the full behavioral burden. 'Observed' vs 'forecast' implies a read-only lookup of measured data rather than a mutation, which is genuinely useful, but nothing is said about data freshness, units, coverage failures for unknown site codes, or the shape of the response.

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 short sentences with zero filler, and the primary purpose is front-loaded before the operational details. Every sentence earns its place.

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 annotations, no output schema, and 0% schema coverage, the definition still covers purpose, both parameters, and the lookup dependency. The remaining gap is what an agent gets back (units, observation timestamp, error behavior for invalid site codes).

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% and neither parameter has a description, so the text must compensate — and it largely does: it constrains 'lang' to 'en or fr' (which the schema does not, it only defaults to en) and explains where site_code comes from. Missing only format/case expectations for site_code itself.

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?

Specific verb + resource + scope: 'Current observed weather conditions for a location by site code.' The word 'current observed' cleanly separates it from the forecast siblings (get_daily_forecast, get_hourly_forecast) and from get_air_quality without needing to open 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?

It supplies the prerequisite workflow explicitly: 'Get the site code from search_locations,' which tells an agent how to obtain the required input rather than guessing. It stops short of stating when to prefer this over the forecast tools, but the implicit condition (you want now, not later) is clear from the purpose line.

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