weather_now

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

No annotations are provided, so the description carries the full burden. It discloses the data source (China Weather Network) and key behavioral outputs (running heat assessment, pace ratio), which is helpful. However, it does not mention whether the tool caches data, latency expectations, or any rate limits, which would be valuable for an agent.

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?

The description is concise with 4 sentences, front-loading the main purpose and output, then adding details on data fields, source, and usage. Every sentence adds value except possibly the last sentence which partially repeats the first sentence's intent.

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?

Given the tool's moderate complexity (one param, no nested objects, output schema present), the description is reasonably complete. It covers what data is returned, the use case, and the input format. The presence of an output schema reduces the need to document return values, so this is sufficient.

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?

With 0% schema description coverage and only 1 parameter (city), the description compensates by stating it supports city names or 9-digit city codes, and providing a default of '成都'. This adds useful meaning beyond the schema, but the description does not explain the format of the city code or give examples, so it's adequate but not comprehensive.

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 clearly states the tool provides real-time weather data including temperature, humidity, WBGT, etc., and specifically adds running heat stress assessment and pace reduction ratio. It distinguishes itself from unrelated sibling tools, though it doesn't contrast with similar weather-focused siblings like weather_forecast or weather_at.

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 explicitly says to use this tool before running to judge if planned pace is feasible, which gives clear usage context. However, it does not mention when to avoid it or suggest alternatives among the 50+ sibling tools, missing an opportunity to differentiate from weather_forecast or weather_at.

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