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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so safety is covered. The description usefully enumerates the returned measurement types, but it says nothing about failure modes for unknown cities, live data freshness, or units.

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?

One front-loaded sentence with the resource scope, followed by a compact example; no filler. The example largely duplicates the schema's examples array, so it is slightly redundant rather than harmful.

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 listing the returned fields (温度/天气现象/风力/湿度). Units and forecast-horizon limits are left to the schema, which is acceptable for a two-parameter read-only tool.

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 100% — city and days (1-7, default 1) are fully documented in the schema. The description only restates the query intent and an example that mirrors the schema's own examples, adding little beyond it, so baseline 3 applies.

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: "查询指定城市的当前天气与未来数日预报" naming the returned fields (温度/天气现象/风力/湿度). No sibling tool covers weather, so differentiation is unnecessary, though the description never says so 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?

Usage is implied by the phrasing (query current weather vs multi-day forecast controlled by days), and the example shows a forecast call. It gives no explicit when-to-use/when-not guidance or pointers to any alternative.

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