悬停

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

With no annotations, the description carries the full burden. It discloses that the tool '派发鼠标移动事件' (dispatches mouse movement events) and '可能触发 CSS 悬停效果' (may trigger CSS hover effects), which reveals the synthetic nature of the action and its potential to cause side effects. This goes beyond a simple 'move mouse' statement, though it omits any error or timeout behavior.

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 two short sentences, front-loaded with the primary action and then a behavioral note. Every sentence serves a purpose without unnecessary filler, making it extremely concise and well-structured.

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?

For a relatively simple hover tool, the description covers the core action, common use case, and a key behavioral nuance. The schema fully documents parameters, and while there is no output schema or annotation, the description provides sufficient context for an agent to understand the tool's purpose and side effects. Minor gaps remain, such as explicit success/error behavior, but these are not critical for a basic hover operation.

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 input schema already provides detailed descriptions for all three parameters (ref, timeout, selector) with mutual exclusivity and default values. The tool description adds no additional parameter meaning, so it meets the baseline of 3 as the schema does the heavy lifting.

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 uses a specific verb+resource structure ('把鼠标移动到元素上方') and clearly distinguishes itself from siblings like web_click by stating its common use case ('常用于触发悬停菜单与提示'). The action is unambiguous and differentiates well from click, type, and scroll tools.

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?

Provides clear context for when to use ('常用于触发悬停菜单与提示'), implying the tool is for hover-triggered UI interactions. However, it does not explicitly mention when not to use or name alternative tools, so it lacks explicit exclusions.

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