scan_duplicates

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

在没有任何 annotations 的情况下，描述额外披露了内部执行逻辑：先按文件大小初筛，只对大小相同的文件做内容 hash，并说明这是为了性能更友好。这比单纯的 '扫描重复文件' 提供了更多行为预期。

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?

描述只有两句话，第一句直接说明结果形式和核心功能，第二句补充关键算法优化，信息密度高且没有冗余。可释放空间估算和性能提示都服务于调用决策。

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?

有输出 schema，因此返回结构不需要额外解释。描述覆盖了功能、输出形式、性能行为和基本输入场景，整体足够完整；唯一略缺的是与兄弟工具的显式对比。

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?

输入 schema 覆盖了全部参数（dirs、min_size_mb），描述本身没有新增参数语义。按照 schema_description_coverage 100% 的基线，评为 3 分是合适的。

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?

描述明确说明了工具行为：按内容 hash 查找重复文件，并按重复组返回且附带可释放空间估算。它与 scan_large、scan_by_ext 等兄弟工具形成清晰区分，核心是 'duplicate' 而不是大小、扩展名或旧文件。动词和资源都具体，意图一目了然。

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?

描述隐含了使用场景：当需要查找重复文件并估算可释放空间时使用。但没有显式说明何时不应使用本工具，或与其他 scan_* 兄弟工具的替代关系，缺乏明确的选择边界。

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