element_getBoundingClientRect

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

没有注解，描述承担全部行为披露责任。完整说明了返回值（rect、dataset、id）、错误行为、跨组件查询机制（内部使用>>>）、选择器限制以及[index=N]的限制。对行为的透明性非常好。

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?

描述为一段长文本，但信息组织有序，先核心功能后细节，每句话都有价值。可以更结构化（如分点），但整体仍算简洁有效。

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?

对于没有输出schema的工具，描述完整涵盖了返回值、边角情况、错误处理、跨组件用法和选择器限制，没有明显信息缺口。

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覆盖率仅25%（只有connection有描述），描述中对selector和innerSelector的用法提供了额外含义，但未提及maxBytes参数。整体上，描述为selector和innerSelector增加了语义，弥补了schema的不足，但遗漏了一个参数。

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?

明确说明工具功能：获取元素相对视口的边界矩形（left/top/width/height/right/bottom），并强调是CSS transform后的实际渲染尺寸。还提到返回dataset和id，并对比了element_getAttributes，清晰区分了用途。

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?

提供了详尽的使用指导：说明何时使用此工具（读取卡片/组件绑定数据），对比了element_getAttributes的不足；支持跨组件查询的用法（selector和innerSelector）；明确限制（仅支持ID/类选择器，[index=N]不能与innerSelector共用）；以及错误处理（未返回矩形时抛错，无法区分元素不存在与display:none）。

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