Scrolls the mouse wheel at specified screen coordinates to move content vertically in a window, with optional verification of the scroll result.
在指定坐标滚动滚轮。delta 为负向下、正向上，通常 120 为一格。
| Name | Required | Description | Default |
|---|---|---|---|
| x | Yes | ||
| y | Yes | ||
| delta | No | 默认 -120（向下一格） | |
| verify | No | ||
| verifyRegion | No | 只比对这块矩形（传目标窗口的 rect），不传则全屏 |
Changes observed during successful MCP inspections.
v0.2.2Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full behavioral burden. It discloses delta sign/direction, but says nothing about the verify/verifyRegion verification flow, what happens after scroll, what is returned, or whether the operation is synchronous — a major gap for a tool with a built-in verification mechanism.
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?
Two short sentences with the core action and the most important parameter detail front-loaded. No wasted text, though it is quite terse given the tool's complexity.
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 5-parameter tool featuring a nested verifyRegion object and a verify flag (a verification feature), the description omits any explanation of that mechanism, which is a substantial omission given no annotations and no output schema offsetting it.
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 coverage is only 40%. The description usefully expands delta (positive = up, 120 per notch) beyond the schema's default note, but leaves verify and verifyRegion unexplained, and verify has no schema description at all. Partial compensation for the coverage gap.
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?
States a specific verb and resource: scrolling the wheel at a given coordinate, which is distinct from siblings like desktop_click or desktop_move. It does not explicitly contrast with those siblings, but the action itself is unambiguous.
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 explains delta semantics but gives no guidance on when to use this tool versus alternatives (e.g., desktop_perceive, desktop_click) or any prerequisites/conditions. An agent must infer the usage context entirely.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.