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Scroll

scroll

Bring off-screen content into view by moving up, down, left, or right by a defined number of lines, optionally over a specific element, before capturing the UI state or taking a screenshot.

Instructions

Scroll up, down, left or right by a number of lines, over element_id when given so the right pane scrolls. Use it to bring off-screen content into view before get_app_state or screenshot. It only scrolls; nothing is clicked or selected. On macOS it scrolls the target app in the background without moving the user's pointer. On Windows and Linux, without element_id it scrolls whatever is under the user's pointer, and an element with no background route gets the real pointer moved onto it (the result then says via cursor).

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
xNoScreen x to scroll over. Remote control only: the pointer moves there first. Ignored otherwise.
yNoScreen y to scroll over. Remote control only: the pointer moves there first. Ignored otherwise.
amountNoNumber of scroll lines, 1 to 100 (default 5)
directionNoScroll direction (default down)
element_idNoElement to scroll, from get_app_state; the nearest scrollable area around it moves. Omit to scroll the last inspected app (macOS) or whatever is under the pointer (Windows, Linux).

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed2 schema fields changedv0.4.2
    • addedInput schema / properties / x
      Added value: +{
+  "description": "Screen x to scroll over. Remote control only: the pointer moves there first. Ignored otherwise.",
+  "type": "number"
+}
    • addedInput schema / properties / y
      Added value: +{
+  "description": "Screen y to scroll over. Remote control only: the pointer moves there first. Ignored otherwise.",
+  "type": "number"
+}
  2. Changed2 schema fields changedv0.4.0
    • changedInput schema / properties / amount / description
      Previous value: -"Number of scroll lines (default 5)"New value: +"Number of scroll lines, 1 to 100 (default 5)"
    • changedInput schema / properties / element_id / description
      Previous value: -"Element to position the pointer over before scrolling, from get_app_state. Omit to scroll at the current pointer position."New value: +"Element to scroll, from get_app_state; the nearest scrollable area around it moves. Omit to scroll the last inspected app (macOS) or whatever is under the pointer (Windows, Linux)."
  3. Changed3 schema fields changedv0.3.1
    • changedInput schema / properties / amount / description
      Previous value: -"Scroll lines (default 5)"New value: +"Number of scroll lines (default 5)"
    • addedInput schema / properties / direction / description
      Added value: +"Scroll direction (default down)"
    • addedInput schema / properties / element_id / description
      Added value: +"Element to position the pointer over before scrolling, from get_app_state. Omit to scroll at the current pointer position."
  4. First observedv0.3.0

TDQS

A4.5/5.0
Behavior4/5

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

Annotations provide limited behavioral info (readOnlyHint false, destructiveHint false), so the description carries the burden. It discloses that it only scrolls (no clicks/selection), background behavior on macOS, and pointer movement implications on Windows/Linux, plus the result causing 'via cursor' note. This is thorough, though it could mention side effects more explicitly.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is dense but well-organized, starting with the core action and purpose, then key exclusions, followed by platform-specific details. It is efficient, though slightly long; but every sentence adds necessary nuance.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given 5 parameters, no required ones, and no output schema, the description covers the essential usage scenarios, platform differences, and limitations. It lacks explicit information about the return value (e.g., success indication), but the output schema is absent, so that may be acceptable. Overall, it is complete enough for an agent to invoke correctly.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, but many parameter descriptions are brief (e.g., 'Screen x to scroll over' with 'Ignored otherwise'). The description adds context by explaining when x/y are ignored (remote control only) and clarifies element_id usage across platforms, adding value beyond the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool scrolls in four directions by lines, optionally over an element, with the specific purpose of bringing off-screen content into view before get_app_state or screenshot. This distinguishes it from siblings like click, hover, and drag, which interact differently.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

It explicitly says when to use it (to bring off-screen content into view before get_app_state or screenshot) and what it does not do (nothing is clicked or selected). It also explains platform-specific behaviors (macOS vs Windows/Linux), alerting the agent to considerations like pointer movement and background scrolling.

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

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