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

Annotations already carry readOnly/idempotent/openWorld, so the description correctly focuses on traits annotations cannot express: the 75 km coverage radius, the 'nearest live relay' sourcing, and a signed receipt for provenance. It stops short of saying what happens when no relay falls within 75 km, which is the one behavioral edge case that matters here.

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?

A single dense sentence front-loads the resource and its returned fields, then closes with the input form. No filler, no restatement of the title.

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 output schema, the description does the right thing by enumerating the returned measurements and units. The remaining gap is failure/coverage behavior — no indication of the response when no relay is within 75 km or when a city name is ambiguous.

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 baseline is 3. The sentence 'Send latitude and longitude, or a city' hints at the coordinate/city alternative, but it does not state that the two modes are mutually exclusive or which takes precedence if both are passed, and all three parameters are optional in the schema.

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 resource (current weather) and enumerates the exact quantities returned with units (temperature °C, humidity %, pressure hPa, wind m/s), plus the data source (Open-Meteo relay). It distinguishes itself from air_quality_now by domain but never names the sibling, so the differentiation is implicit rather than explicit.

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?

The description only tells the agent how to supply input ('Send latitude and longitude, or a city') — that is parameter syntax, not usage guidance. There is no statement of when to prefer this over air_quality_now or nearby_sensors, and no exclusions or prerequisites.

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