Scroll down the screen with a bottom-to-top swipe on a specified device, enabling mobile UI tests to navigate content areas that require vertical scrolling.
Scroll down on the screen (swipe from bottom to top)
| Name | Required | Description | Default |
|---|---|---|---|
| device_id | No | Target device ID. If omitted, uses the default device. |
Changes observed during successful MCP inspections.
v3.8.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden of behavioral disclosure. It only states the mechanical action without mentioning any side effects, scroll extent, speed, or whether it operates on the whole screen or a focused element. This is minimal disclosure for a UI control tool.
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, clear sentence with no filler. It is front-loaded with the primary action and adds the gesture detail efficiently.
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 simple scrolling action, the description provides the essential information. However, with no annotations and no output schema, an agent might benefit from knowing whether this scrolls the entire screen, whether it waits for scrolling to finish, or how far it scrolls. These gaps make it adequate but not complete.
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 single parameter device_id is fully described in the schema (covers 100%), and the description adds no extra meaning. Since schema coverage is high, the baseline of 3 is appropriate; the description does not compensate further.
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 action (scroll down) and the specific gesture (swipe from bottom to top). This distinguishes it from the sibling scroll_up, which would imply the opposite direction, so an agent can immediately infer the tool's purpose.
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 provides no guidance on when to use this tool versus alternatives like swipe or scroll_up. It doesn't state any context, prerequisites, or conditions that would help an agent decide between this and other scrolling-related tools.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.