cls_describe_regions

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

With no annotations provided, the description carries full burden. It effectively describes the tool's behavior: it's a read-only query (implied by '查询'), returns specific data fields (region IDs and Chinese names), and has no parameters. It doesn't mention rate limits, authentication needs, or pagination, but for a simple metadata query tool, the description provides adequate behavioral context.

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 well-structured with clear sections (### 无需参数, ### 返回信息, ### 使用场景), front-loads the core purpose, and every sentence adds value. No redundant information or wasted words.

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 simplicity (0 parameters, read-only query, has output schema), the description is complete. It explains what the tool does, when to use it, what it returns, and that no parameters are needed. The output schema will handle return value documentation, so the description appropriately focuses on usage context.

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 tool has 0 parameters with 100% schema description coverage. The description explicitly states '无需参数' (no parameters needed) and '直接调用即可' (call directly), which adds helpful confirmation beyond the empty schema. This exceeds the baseline expectation for parameterless tools.

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's purpose as '查询 CLS 支持的地域列表' (query CLS supported region list), specifying both the verb (query) and resource (region list). It distinguishes itself from siblings by focusing on region metadata rather than logs, alarms, dashboards, or other CLS resources mentioned in sibling tool names.

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 provides usage scenarios: '不确定某个城市/地区对应的地域 ID 时，先调用此工具查询' (when unsure about region ID for a city/area, call this tool first) and '需要列出所有可用地域供用户选择时使用' (use when needing to list all available regions for user selection). This gives clear when-to-use guidance with practical examples.

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