agent-device

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scroll

Move device content in a chosen direction or to top/bottom edges; optionally repeat until a target selector becomes visible.

Instructions

Scroll in a direction, or toward the top/bottom edge of scrollable content. Set until to a selector to reach an off-screen target in one command rather than a scroll-and-check loop. The optional amount is the finger-path fraction of the viewport axis, honored up to 0.8 of it; directional scrolls reduce release momentum, while app scroll physics determine the final content offset. A visible keyboard shortens the swiped band instead of being dismissed; when too little is left, the command refuses with scroll_keyboard_occludes_surface. Times out after 90s; a caller-supplied budget extends it.

Input Schema

TableJSON Schema

Name	Required	Description
`udid`	No	Apple device or simulator UDID; the selector that pins one device when several share a name.
`debug`	No	Enable debug diagnostics.
`runId`	No	Lease run identifier.
`until`	No	Repeat scroll passes until this selector is visible on screen, then stop. Not valid with the top/bottom edge directions, which carry their own stop condition.
`amount`	No	Platform scroll amount.
`device`	No	Device name selector (a UDID belongs in udid, a serial in serial).
`pixels`	No	Pixel scroll amount.
`serial`	No	Android, HarmonyOS, or Vega VVD serial selector.
`settle`	No	After the action, wait for the UI to go quiet and return the settled diff vs the pre-action tree in the same response. Best-effort; never fails the action.
`target`	No	Alias for deviceTarget on commands without a UI target field. Interaction commands reserve target for the UI element.
`tenant`	No	Remote tenant identifier.
`leaseId`	No	Existing lease identifier.
`session`	No	Agent-device session name.
`noRecord`	No	Do not record this action.
`platform`	No	Platform selector used to resolve a device.
`direction`	Yes
`timeoutMs`	No	Settle: wait deadline in milliseconds (default 10000).
`durationMs`	No	Scroll duration in milliseconds when the backend supports pacing.
`includeCost`	No	Include per-command agent-cost (cost.wallClockMs, …) in structuredContent. Defaults to off; the default response shape is unchanged.
`deviceTarget`	No	Device target form. Maps to the CLI --target flag.
`responseLevel`	No	Response verbosity: token-cheap digest / default (today) / full. Defaults to default; the default response shape is unchanged.
`settleQuietMs`	No	Settle: quiet window in milliseconds (default 500).
`mcpOutputFormat`	No	MCP text content format. Defaults to optimized agent-friendly text; use json for JSON text. Structured content is always returned separately.
`androidDeviceAllowlist`	No	Android serial allowlist used for device resolution.

Output Schema

TableJSON Schema

Name	Required	Description
`edge`	No
`until`	No	Until scrolls only: the selector the passes stopped on.
`amount`	No
`passes`	No	Edge and until scrolls only: how many scroll-and-check passes ran.
`pixels`	No
`settle`	No
`message`	No
`direction`	Yes
`durationMs`	No
`keyboardMinY`	No	Where the keyboard began, in the same unit as the gesture coordinates. Clipped scrolls only.
`keyboardAvoided`	No	Present only when an on-screen keyboard forced the swipe into the band above it; the reported pixels were planned against the shorter referenceHeight.

Schema Changelog

Changes observed during successful MCP inspections.

Changed6 schema fields changedv0.21.2Sep 16, 2026

addedInput schema / properties / until

Added value: +{
+  "description": "Repeat scroll passes until this selector is visible on screen, then stop. Not valid with the top/bottom edge directions, which carry their own stop condition.",
+  "type": "string"
+}

addedOutput schema / properties / keyboardAvoided

Added value: +{
+  "description": "Present only when an on-screen keyboard forced the swipe into the band above it; the reported pixels were planned against the shorter referenceHeight.",
+  "type": "boolean"
+}

addedOutput schema / properties / keyboardMinY

Added value: +{
+  "description": "Where the keyboard began, in the same unit as the gesture coordinates. Clipped scrolls only.",
+  "type": "number"
+}

changedOutput schema / properties / passes / description

Previous value: -"Edge scrolls only: how many scroll-and-check passes ran."New value: +"Edge and until scrolls only: how many scroll-and-check passes ran."

addedOutput schema / properties / settle / properties / surfaceChange

Added value: +{
+  "description": "Present when an in-place system surface (web sign-in or Apple Pay sheet) was presented over the app, or left it.",
+  "properties": {
+    "disclosure": {
+      "description": "Agent-facing sentence explaining the surface transition.",
+      "type": "string"
+    },
+    "from": {
+      "description": "Surface the pre-action baseline described: a host bundle id, or app.",
+      "type": "string"
+    },
+    "to": {
+      "description": "Surface the post-action capture describes: a host bundle id, or app.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "from",
+    "to",
+    "disclosure"
+  ],
+  "type": "object"
+}

addedOutput schema / properties / until

Added value: +{
+  "description": "Until scrolls only: the selector the passes stopped on.",
+  "type": "string"
+}

Changed3 schema fields changedv0.21.0Sep 9, 2026

changedInput schema / properties / device / description

Previous value: -"Device name selector."New value: +"Device name selector (a UDID belongs in udid, a serial in serial)."

changedInput schema / properties / serial / description

Previous value: -"Android device or Vega VVD serial selector."New value: +"Android, HarmonyOS, or Vega VVD serial selector."

changedInput schema / properties / udid / description

Previous value: -"iOS device UDID selector."New value: +"Apple device or simulator UDID; the selector that pins one device when several share a name."

Changed9 schema fields changedv0.20.10Aug 26, 2026

removedInput schema / properties / cwd

Removed value: -{
-  "description": "Working directory for command execution.",
-  "type": "string"
-}

removedInput schema / properties / daemonAuthToken

Removed value: -{
-  "description": "Remote daemon auth token.",
-  "type": "string"
-}

removedInput schema / properties / daemonBaseUrl

Removed value: -{
-  "description": "Remote daemon base URL.",
-  "type": "string"
-}

removedInput schema / properties / iosSimulatorDeviceSet

Removed value: -{
-  "description": "iOS simulator device-set path used for device resolution.",
-  "type": "string"
-}

removedInput schema / properties / iosXctestDerivedDataPath

Removed value: -{
-  "description": "Derived data path for external iOS XCTest runner execution.",
-  "type": "string"
-}

removedInput schema / properties / iosXctestEnvDir

Removed value: -{
-  "description": "Writable directory for iOS XCTest runner env overlays.",
-  "type": "string"
-}

removedInput schema / properties / iosXctestrunFile

Removed value: -{
-  "description": "Externally built iOS XCTest runner .xctestrun artifact path.",
-  "type": "string"
-}

removedInput schema / properties / stateDir

Removed value: -{
-  "description": "Agent-device state directory.",
-  "type": "string"
-}

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "properties": {
+    "amount": {
+      "type": "number"
+    },
+    "direction": {
+      "enum": [
+        "up",
+        "down",
+        "left",
+        "right"
+      ],
+      "type": "string"
+    },
+    "durationMs": {
+      "type": "number"
+    },
+    "edge": {
+      "enum": [
+        "top",
+        "bottom"
+      ],
+      "type": "string"
+    },
+    "message": {
+      "type": "string"
+    },
+    "passes": {
+      "description": "Edge scrolls only: how many scroll-and-check passes ran.",
+      "type": "number"
+    },
+    "pixels": {
+      "type": "number"
+    },
+    "settle": {
+      "properties": {
+        "captures": {
+          "type": "number"
+        },
+        "diff": {
+          "description": "Settled diff vs the pre-action tree (changed lines only).",
+          "properties": {
+            "lines": {
+              "items": {
+                "properties": {
+                  "kind": {
+                    "enum": [
+                      "added",
+                      "removed"
+                    ],
+                    "type": "string"
+                  },
+                  "ref": {
+                    "description": "Plain ref body (e12) for added lines.",
+                    "type": "string"
+                  },
+                  "text": {
+                    "type": "string"
+                  }
+                },
+                "required": [
+                  "kind",
+                  "text"
+                ],
+                "type": "object"
+              },
+              "type": "array"
+            },
+            "summary": {
+              "properties": {
+                "additions": {
+                  "type": "number"
+                },
+                "removals": {
+                  "type": "number"
+                },
+                "unchanged": {
+                  "type": "number"
+                }
+              },
+              "required": [
+                "additions",
+                "removals",
+                "unchanged"
+              ],
+              "type": "object"
+            },
+            "truncated": {
+              "description": "Lines were capped to the response bound.",
+              "type": "boolean"
+            }
+          },
+          "required": [
+            "summary",
+            "lines"
+          ],
+          "type": "object"
+        },
+        "hint": {
+          "type": "string"
+        },
+        "quietMs": {
+          "type": "number"
+        },
+        "refs": {
+          "items": {
+            "properties": {
+              "ref": {
+                "description": "Plain ref body (e12) minted from the stored settled tree.",
+                "type": "string"
+              }
+            },
+            "required": [
+              "ref"
+            ],
+            "type": "object"
+          },
+          "type": "array"
+        },
+        "refsGeneration": {
+          "description": "Snapshot generation of the stored settled tree; refs on added diff lines were minted from it.",
+          "type": "number"
+        },
+        "settled": {
+          "description": "Whether the UI held the quiet window before the deadline. false is advisory, not failure.",
+          "type": "boolean"
+        },
+        "tail": {
+          "description": "Unchanged interactive refs tail: still-present, actionable elements from the settled tree, attached only when diff carries zero added-line refs (a modal-dismiss/toast-only diff).",
+          "items": {
+            "properties": {
+              "label": {
+                "type": "string"
+              },
+              "ref": {
+                "description": "Plain ref body (e12) minted from the stored settled tree.",
+                "type": "string"
+              },
+              "role": {
+                "type": "string"
+              }
+            },
+            "required": [
+              "ref",
+              "role"
+            ],
+            "type": "object"
+          },
+          "type": "array"
+        },
+        "tailTruncated": {
+          "description": "Present (true) when tail candidates exceeded the response cap.",
+          "type": "boolean"
+        },
+        "timeoutMs": {
+          "type": "number"
+        },
+        "waitedMs": {
+          "type": "number"
+        }
+      },
+      "required": [
+        "settled",
+        "waitedMs",
+        "captures",
+        "quietMs",
+        "timeoutMs"
+      ],
+      "type": "object"
+    }
+  },
+  "required": [
+    "direction"
+  ],
+  "type": "object"
+}

Changed1 schema field changedv0.20.9Aug 19, 2026

changedInput schema / properties / platform / enum

Previous value: -[
-  "apple",
-  "android",
-  "vega",
-  "linux",
-  "web",
-  "ios",
-  "macos"
-]New value: +[
+  "apple",
+  "android",
+  "harmonyos",
+  "vega",
+  "linux",
+  "web",
+  "ios",
+  "macos"
+]

Changed3 schema fields changedv0.20.6Aug 7, 2026

addedInput schema / properties / settle

Added value: +{
+  "description": "After the action, wait for the UI to go quiet and return the settled diff vs the pre-action tree in the same response. Best-effort; never fails the action.",
+  "type": "boolean"
+}

addedInput schema / properties / settleQuietMs

Added value: +{
+  "description": "Settle: quiet window in milliseconds (default 500).",
+  "minimum": 0,
+  "type": "integer"
+}

addedInput schema / properties / timeoutMs

Added value: +{
+  "description": "Settle: wait deadline in milliseconds (default 10000).",
+  "minimum": 1,
+  "type": "integer"
+}

Changed3 schema fields changedv0.20.2Jul 30, 2026

addedInput schema / properties / noRecord

Added value: +{
+  "description": "Do not record this action.",
+  "type": "boolean"
+}

changedInput schema / properties / platform / enum

Previous value: -[
-  "apple",
-  "android",
-  "linux",
-  "web",
-  "ios",
-  "macos"
-]New value: +[
+  "apple",
+  "android",
+  "vega",
+  "linux",
+  "web",
+  "ios",
+  "macos"
+]

changedInput schema / properties / serial / description

Previous value: -"Android serial selector."New value: +"Android device or Vega VVD serial selector."

Changed3 schema fields changedv0.17.11Jul 6, 2026

addedInput schema / properties / includeCost

Added value: +{
+  "description": "Include per-command agent-cost (cost.wallClockMs, …) in structuredContent. Defaults to off; the default response shape is unchanged.",
+  "type": "boolean"
+}

changedInput schema / properties / platform / enum

Previous value: -[
-  "ios",
-  "macos",
-  "android",
-  "linux",
-  "web",
-  "apple"
-]New value: +[
+  "apple",
+  "android",
+  "linux",
+  "web",
+  "ios",
+  "macos"
+]

addedInput schema / properties / responseLevel

Added value: +{
+  "description": "Response verbosity: token-cheap digest / default (today) / full. Defaults to default; the default response shape is unchanged.",
+  "enum": [
+    "digest",
+    "default",
+    "full"
+  ],
+  "type": "string"
+}

Changed1 schema field changedv0.17.9Jun 25, 2026

addedInput schema / properties / durationMs

Added value: +{
+  "description": "Scroll duration in milliseconds when the backend supports pacing.",
+  "maximum": 10000,
+  "minimum": 0,
+  "type": "integer"
+}

Changed1 schema field changedv0.17.7Jun 23, 2026

changedInput schema / properties / platform / enum

Previous value: -[
-  "ios",
-  "macos",
-  "android",
-  "linux",
-  "apple"
-]New value: +[
+  "ios",
+  "macos",
+  "android",
+  "linux",
+  "web",
+  "apple"
+]

Changed5 schema fields changedv0.17.6Jun 18, 2026

addedInput schema / properties / iosXctestDerivedDataPath

Added value: +{
+  "description": "Derived data path for external iOS XCTest runner execution.",
+  "type": "string"
+}

addedInput schema / properties / iosXctestEnvDir

Added value: +{
+  "description": "Writable directory for iOS XCTest runner env overlays.",
+  "type": "string"
+}

addedInput schema / properties / iosXctestrunFile

Added value: +{
+  "description": "Externally built iOS XCTest runner .xctestrun artifact path.",
+  "type": "string"
+}

addedInput schema / properties / mcpOutputFormat

Added value: +{
+  "description": "MCP text content format. Defaults to optimized agent-friendly text; use json for JSON text. Structured content is always returned separately.",
+  "enum": [
+    "optimized",
+    "json"
+  ],
+  "type": "string"
+}

changedInput schema / properties / platform / enum

Previous value: -[
-  "ios",
-  "android",
-  "macos",
-  "linux",
-  "apple"
-]New value: +[
+  "ios",
+  "macos",
+  "android",
+  "linux",
+  "apple"
+]

First observedv0.16.9Jun 3, 2026

TDQS

A4.7/5.0

Behavior5/5

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

With no annotations provided, the description carries the full behavioral disclosure burden and does so well. It discloses the finger-path cap, release momentum reduction, app-driven scroll physics, keyboard handlin g, a specific error name, and the 90-second timeout with caller budget extension. This is unusually thorough for a scroll command.

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

Conciseness5/5

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

The description is dense but well organized, front-loading the core purpose before edge cases. Every sentence adds operational value—targeting, amount semantics, momentum, keyboard occlusion, and timeout—without redundant filler.

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

Completeness5/5

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

Given a 24-parameter tool with an output schema and 96% schema coverage, the description supplies the missing behavioral context: timeout, budget extension, keyboard occlusion, and scroll physics. An agent has everything needed to invoke the tool correctly and predict failure cases.

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 description coverage is 96%, so the baseline is 3, but the description adds meaning to otherwise vague schema fields. It interprets `amount` as a finger-path fraction of the viewport axis and clarifies `until` as a repeat-until-target-visible mechanism, going beyond the schema's terse 'Platform scroll amount'.

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 names a specific action—scroll in a direction or toward the top/bottom edge—and adds the `until` option for reaching off-screen content in one command. This clearly distinguishes the tool from sibling gesture/swipe alternatives even without naming them.

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

Usage Guidelines4/5

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

It gives explicit guidance for when to use `until` ('reach an off-screen target in one command rather than a scroll-and-check loop') and explains important constraints such as the 0.8 amount cap and the keyboard occlusion refusal. It does not explicitly contrast with `swipe` or other siblings, but the usage context is otherwise clear.

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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Output Schema

Schema Changelog

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