browser_screenshotElement

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

No annotations are provided, so the description carries the full burden for behavioral disclosure. The description only states the action without mentioning any side effects, prerequisites, or how the screenshot is returned. It does not mention that the element may need to be visible or that the optional 'scrollIntoView' parameter could affect the capture. This lack of behavioral detail is a significant gap.

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 a single, concise sentence that front-loads the primary action and provides illustrative examples. It is efficient and easy to scan, with no unnecessary words or redundancy.

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 simplicity of the tool, the description provides enough context for basic usage, but it lacks any mention of the output format or what the agent should expect as a return value. Since there is no output schema and no annotations, the description should clarify that a screenshot image or file is returned, but it does not. This leaves a moderate gap.

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 schema already includes descriptions for both parameters with 100% coverage, so the baseline is 3. The tool description does not add any further meaning beyond what the schema provides. Since the schema is sufficient, no additional points are warranted.

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: '截取页面中某个元素的截图' (take a screenshot of an element on the page), and gives examples such as button, image, and area. This unambiguously distinguishes it from the sibling tool 'browser_screenshot' which likely captures the full page.

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 implies usage when a screenshot of a specific element is needed, but it does not explicitly compare with alternatives like the full-page screenshot or PDF sibling tools. There are no clear conditions or exclusions stated, leaving the user to infer when to choose this tool over others.

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