nws_observation_latest

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

Annotations already declare readOnlyHint=true, so the description does not need to restate safe-read behavior. It adds value by disclosing the exact returned measurements (temperature, wind, humidity, pressure, visibility, conditions) and the ICAO format for station IDs, which helps set data expectations.

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?

Three short sentences each serve a distinct purpose: state the main function, list returned data fields, and clarify the parameter format. No filler or redundant phrasing—ideal conciseness for a simple tool.

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?

For a single-parameter read-only tool, the description is sufficient: it explains what the tool returns and how to specify the station. It correctly does not attempt to enumerate all possible output fields (no output schema needed). A small gap is that it does not mention how to discover station IDs (e.g., via nws_stations), but this is not essential for correct invocation.

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?

The input schema already provides 100% coverage of the single parameter, including ICAO code examples. The description essentially repeats this information ('Station IDs are ICAO codes'), adding no new semantic detail beyond what the schema already communicates, so baseline 3 is appropriate.

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 uses a specific verb ('Get') and resource ('latest weather observation from a station'), clearly distinguishing it from siblings like nws_observation_history (history) and nws_forecast (forecast). It also lists the returned fields, making the tool's function immediately obvious.

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 implies clear use context: when you want the latest observation for a known station, as opposed to historical data or forecasts. However, it does not explicitly mention alternatives or exclusions, such as pointing to nws_observation_history for past observations.

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