desktop-touch-mcp

Overview Schema Source Related Servers Discussions Admin

scroll

Navigate window content by sending wheel notches, bringing elements into view, auto-detecting scroll containers, stitching full-page captures, or extracting deduplicated text via OCR.

Instructions

Purpose: Scroll a window or page. 5 strategies via action: 'raw' (wheel notches), 'to_element' (UIA name/automationId or CSS selector), 'smart' (auto-detect target with multi-strategy fallback), 'capture' (full-page stitched image), 'read' (scroll+OCR+dedupe → stitched text). Details: action='raw': send raw mouse-wheel notches at (x,y) or current cursor, optional window focus. Scroll scale — one amount unit is one wheel notch on every dispatch path, and ≈10 notches move one screenful: UIA-capable apps (Notepad, Explorer, WPF) step ≈1/10 of the visible area per notch, browsers and WebView apps (Chrome, Electron, Tauri) ≈100 px. amount:3 (default) ≈ a third of a screen. action='to_element': scroll a named element into viewport (UIA or CDP). action='smart': handles nested scroll layers, virtualised lists, sticky-header occlusion. action='capture': stitches full-page images (caps at ~700KB raw); sizeReduced=true means downscaled. action='read': scrolls page-by-page, OCRs each viewport, deduplicates overlapping lines, returns stitched text; language auto-detected from OS locale if omitted. Prefer: Use action='to_element' or action='smart' for click target out-of-viewport recovery (entity_outside_viewport) — scrolling only helps when the target scrolled out of its own window; if desktop_act reported origin_window_not_visible, restore the window with focus_window and re-run desktop_discover instead. Use action='capture' for reading long pages as images. Use action='read' for extracting text from long native-app documents (PDF readers, text editors, terminals) where copy-paste is unavailable. For simple scroll without target, use action='raw'. Caveats: action='capture' returns stitched image — pixels do NOT match screen coords when sizeReduced=true, use for reading only, not mouse_click. action='smart' CDP path requires browser_open. action='to_element' native path requires element to implement UIA ScrollItemPattern. action='read' uses OCR (imperfect accuracy) and requires the window to be visible; for browser pages prefer browser_eval or browser_overview for accurate DOM text. action='raw' typed errors: code:'ScrollNotDelivered' on silent drop (overlay / non-scrollable / UIPI low-IL); already-at-boundary is success via pre/post-percent disambiguation. hints.verifyDelivery.{channel,reason} per ADR-018 §2.6 — channel is the transport used ('uia'/'cdp'/'postmessage'/'wheel_send_input'); reason='pixel_delta_observed' = pixel evidence only (weak). action='smart' typed errors: code:'OverflowHiddenAncestor' (retry with expandHidden:true), code:'VirtualScrollExhausted' (provide virtualIndex). Examples: scroll({action:'raw', direction:'down', amount:5, windowTitle:'Chrome'}) scroll({action:'to_element', name:'OK', windowTitle:'Dialog'}) scroll({action:'smart', target:'#create-release-btn'}) scroll({action:'capture', windowTitle:'Chrome', maxScrolls:10}) scroll({action:'read', windowTitle:'Acrobat', maxPages:15}) // OCR + dedupe long PDF

Input Schema

TableJSON Schema

Name	Required	Description	Default
`x`	No	X coordinate to scroll at (moves cursor there first)
`y`	No	Y coordinate to scroll at
`hint`	No	Scroll direction hint for binary-search (image path). Seeds lo/hi bounds to reduce attempts.
`hwnd`	No	Direct window handle ID (takes precedence over windowTitle).
`name`	No	Partial name/label of the element (UIA name match). Use for native app elements. At least one of name or selector must be provided.
`port`	No	CDP port for Chrome path (default 9222)
`block`	No	Vertical alignment after scroll — start/center/end/nearest (Chrome path only, default: center)	center
`speed`	No	Cursor movement speed in px/sec (0=teleport, omit=default)
`tabId`	No	Tab ID (Chrome path only). Omit for first page tab.
`action`	Yes	Action selector — one of: raw, to_element, smart, capture, read. Per-action required fields are enforced at call time (see the tool description); this flat schema lists every action's fields as optional.
`amount`	No	Number of scroll notches (default 3, max 1000). One notch = one physical wheel detent on every dispatch path. Count screenfuls, not lines: ≈10 notches move one screenful, so amount:3 (default) is about a third of a screen. UIA-capable apps (Notepad, Explorer, WPF) step ≈1/10 of the window's visible area per notch; browsers and WebView-based apps (Chrome, Electron, Tauri) move ≈100 px per notch. Exact distance depends on the app, the window size and the OS wheel-speed setting. The 1000-notch ceiling exists because each notch is dispatched as real wheel input; to reach a specific place in a long document use action='to_element' or action='smart' instead of a huge amount.
`homing`	No	Apply window-movement homing correction to (x,y) before scrolling. Default true.
`inline`	No	Vertical alignment after scroll (CDP path). Default: center.	center
`target`	No	CSS selector (Chrome/Edge) or partial UIA name (native apps). For CDP path, must be a valid CSS selector (starts with #, ., tag, or [ ). For UIA path, a partial name match against element Name property.
`include`	No	Optional response-shape opt-in. `['envelope']` returns the self-documenting envelope (`_version` / `data` / `as_of` / `confidence`). `['raw']` forces raw shape (overrides DESKTOP_TOUCH_ENVELOPE=1 server default). Default behaviour is raw shape (compat with existing clients).
`language`	No	OCR language code (e.g. 'ja', 'en', 'zh'). Omit to auto-detect from Windows system locale via Intl.DateTimeFormat().resolvedOptions().locale. Default: auto.
`maxDepth`	No	Max number of ancestor scroll containers to walk. Default 3.
`maxPages`	No	Maximum number of scroll steps / OCR pages (default 20, max 50).
`maxWidth`	No	Max size of the short edge of the final image (default 1280). For 'down': caps the image width; height is unconstrained. For 'right': caps the image height; width is unconstrained.
`selector`	No	CSS selector for the element (Chrome/Edge only). At least one of name or selector must be provided.
`strategy`	No	auto (default): try CDP → UIA → image in order. cdp: Chrome/Edge only. uia: native Windows UIA. image: image + Win32 binary-search.	auto
`direction`	No	Scroll direction
`scrollKey`	No	Key sent to scroll one page. PageDown (default): full-page scroll for most apps. Space: web/PDF readers. ArrowDown: line-by-line slow scroll.	PageDown
`maxScrolls`	No	Maximum scroll iterations before stopping (default 10, max 30)
`retryCount`	No	Max scroll attempts (image path binary-search). Default 3, cap 4.
`windowTitle`	No	Partial window title. When provided, the server focuses this window first.
`expandHidden`	No	Temporarily set overflow:hidden ancestors to overflow:auto to unlock scroll. Mutates live CSS.
`virtualIndex`	No	Target row index in a virtualised list (0-based). Enables direct TanStack/data-index seeking.
`virtualTotal`	No	Total row count in a virtualised list. Required when virtualIndex is set.
`scrollDelayMs`	No	Milliseconds to wait after each scroll for rendering to settle (default 400). Increase for slow/animated pages.
`verifyWithHash`	No	Verify scroll effectiveness via perceptual hash comparison. Automatically enabled for image path.
`stopWhenNoChange`	No	Stop automatically when two consecutive pages yield no new lines after deduplication (page-end detection). Default true.

Schema Changelog

Changes observed during successful MCP inspections.

Changed4 schema fields changedv2.0.0Sep 24, 2026

changedInput schema / properties / amount / description

Previous value: -"Number of scroll notches (default 3). UIA-capable apps (Notepad, Explorer, WPF — Tier 1): empirically ≈1 text line per notch; amount:3 (default) ≈ 3 lines (small nudge), amount:10 ≈ 10 lines (~½ visible area). Legacy apps (SendInput path): each amount unit sends 3 wheel ticks; at Windows default 3 lines/tick that is ≈9 text lines per unit — distance varies by app/OS wheel-speed settings."New value: +"Number of scroll notches (default 3, max 1000). One notch = one physical wheel detent on every dispatch path. Count screenfuls, not lines: ≈10 notches move one screenful, so amount:3 (default) is about a third of a screen. UIA-capable apps (Notepad, Explorer, WPF) step ≈1/10 of the window's visible area per notch; browsers and WebView-based apps (Chrome, Electron, Tauri) move ≈100 px per notch. Exact distance depends on the app, the window size and the OS wheel-speed setting. The 1000-notch ceiling exists because each notch is dispatched as real wheel input; to reach a specific place in a long document use action='to_element' or action='smart' instead of a huge amount."

addedInput schema / properties / amount / maximum
```
Added value: +1000
```
addedInput schema / properties / amount / minimum
```
Added value: +1
```
addedInput schema / properties / target / minLength
```
Added value: +1
```

Addedv1.9.2May 25, 2026
Removedv1.8.0May 23, 2026
Addedv1.6.0May 16, 2026
Removedv1.5.1May 12, 2026
Addedv1.5.0May 12, 2026
Removedv1.4.3May 11, 2026
Addedv1.4.2May 10, 2026
Removedv1.4.0May 9, 2026

Changed1 schema field changedv1.2.1May 3, 2026

changedInput schema / oneOf

Previous value: -[
-  {
-    "additionalProperties": false,
-    "properties": {
-      "action": {
-        "const": "raw"
-      },
-      "amount": {
-        "default": 3,
-        "description": "Number of scroll steps (default 3)",
-        "type": "integer"
-      },
-      "direction": {
-        "description": "Scroll direction",
-        "enum": [
-          "up",
-          "down",
-          "left",
-          "right"
-        ],
-        "type": "string"
-      },
-      "homing": {
-        "default": true,
-        "description": "Apply window-movement homing correction to (x,y) before scrolling. Default true."
-      },
-      "hwnd": {
-        "description": "Direct window handle ID (takes precedence over windowTitle).",
-        "type": "string"
-      },
-      "speed": {
-        "description": "Cursor movement speed in px/sec (0=teleport, omit=default)",
-        "type": "number"
-      },
-      "windowTitle": {
-        "description": "Partial window title. When provided, the server focuses this window first.",
-        "type": "string"
-      },
-      "x": {
-        "description": "X coordinate to scroll at (moves cursor there first)",
-        "type": "number"
-      },
-      "y": {
-        "description": "Y coordinate to scroll at",
-        "type": "number"
-      }
-    },
-    "required": [
-      "action",
-      "direction"
-    ],
-    "type": "object"
-  },
-  {
-    "additionalProperties": false,
-    "properties": {
-      "action": {
-        "const": "to_element"
-      },
-      "block": {
-        "default": "center",
-        "description": "Vertical alignment after scroll — start/center/end/nearest (Chrome path only, default: center)",
-        "enum": [
-          "start",
-          "center",
-          "end",
-          "nearest"
-        ],
-        "type": "string"
-      },
-      "name": {
-        "description": "Partial name/label of the element (UIA name match). Use for native app elements. At least one of name or selector must be provided.",
-        "type": "string"
-      },
-      "port": {
-        "default": 9222,
-        "description": "CDP port for Chrome path (default 9222)",
-        "maximum": 65535,
-        "minimum": 1,
-        "type": "integer"
-      },
-      "selector": {
-        "description": "CSS selector for the element (Chrome/Edge only). At least one of name or selector must be provided.",
-        "type": "string"
-      },
-      "tabId": {
-        "description": "Tab ID (Chrome path only). Omit for first page tab.",
-        "type": "string"
-      },
-      "windowTitle": {
-        "description": "Partial window title (required for native path when name is used)",
-        "type": "string"
-      }
-    },
-    "required": [
-      "action"
-    ],
-    "type": "object"
-  },
-  {
-    "additionalProperties": false,
-    "properties": {
-      "action": {
-        "const": "smart"
-      },
-      "direction": {
-        "default": "into-view",
-        "description": "Scroll direction. into-view: scroll until target element is visible (default). Other values scroll unconditionally.",
-        "enum": [
-          "into-view",
-          "up",
-          "down",
-          "left",
-          "right"
-        ],
-        "type": "string"
-      },
-      "expandHidden": {
-        "default": false,
-        "description": "Temporarily set overflow:hidden ancestors to overflow:auto to unlock scroll. Mutates live CSS.",
-        "type": "boolean"
-      },
-      "hint": {
-        "description": "Scroll direction hint for binary-search (image path). Seeds lo/hi bounds to reduce attempts.",
-        "enum": [
-          "above",
-          "below",
-          "left",
-          "right"
-        ],
-        "type": "string"
-      },
-      "inline": {
-        "default": "center",
-        "description": "Vertical alignment after scroll (CDP path). Default: center.",
-        "enum": [
-          "start",
-          "center",
-          "end",
-          "nearest"
-        ],
-        "type": "string"
-      },
-      "maxDepth": {
-        "default": 3,
-        "description": "Max number of ancestor scroll containers to walk. Default 3.",
-        "maximum": 10,
-        "minimum": 1,
-        "type": "integer"
-      },
-      "port": {
-        "default": 9222,
-        "description": "CDP port (default 9222)",
-        "maximum": 65535,
-        "minimum": 1,
-        "type": "integer"
-      },
-      "retryCount": {
-        "default": 3,
-        "description": "Max scroll attempts (image path binary-search). Default 3, cap 4.",
-        "maximum": 4,
-        "minimum": 1,
-        "type": "integer"
-      },
-      "strategy": {
-        "default": "auto",
-        "description": "auto (default): try CDP → UIA → image in order. cdp: Chrome/Edge only. uia: native Windows UIA. image: image + Win32 binary-search.",
-        "enum": [
-          "auto",
-          "cdp",
-          "uia",
-          "image"
-        ],
-        "type": "string"
-      },
-      "tabId": {
-        "description": "CDP tab ID (Chrome path only). Omit for first page tab.",
-        "type": "string"
-      },
-      "target": {
-        "description": "CSS selector (Chrome/Edge) or partial UIA name (native apps). For CDP path, must be a valid CSS selector (starts with #, ., tag, or [ ). For UIA path, a partial name match against element Name property.",
-        "type": "string"
-      },
-      "verifyWithHash": {
-        "default": false,
-        "description": "Verify scroll effectiveness via perceptual hash comparison. Automatically enabled for image path.",
-        "type": "boolean"
-      },
-      "virtualIndex": {
-        "description": "Target row index in a virtualised list (0-based). Enables direct TanStack/data-index seeking.",
-        "minimum": 0,
-        "type": "integer"
-      },
-      "virtualTotal": {
-        "description": "Total row count in a virtualised list. Required when virtualIndex is set.",
-        "minimum": 1,
-        "type": "integer"
-      },
-      "windowTitle": {
-        "description": "Partial window title. Required for UIA and image paths. For CDP path, optional.",
-        "type": "string"
-      }
-    },
-    "required": [
-      "action",
-      "target"
-    ],
-    "type": "object"
-  },
-  {
-    "additionalProperties": false,
-    "properties": {
-      "action": {
-        "const": "capture"
-      },
-      "direction": {
-        "default": "down",
-        "description": "Scroll direction: 'down' (vertical, uses Page Down key) or 'right' (horizontal, uses mouse scroll). Default 'down'.",
-        "enum": [
-          "down",
-          "right"
-        ],
-        "type": "string"
-      },
-      "maxScrolls": {
-        "default": 10,
-        "description": "Maximum scroll iterations before stopping (default 10, max 30)",
-        "maximum": 30,
-        "minimum": 1,
-        "type": "integer"
-      },
-      "maxWidth": {
-        "default": 1280,
-        "description": "Max size of the short edge of the final image (default 1280). For 'down': caps the image width; height is unconstrained. For 'right': caps the image height; width is unconstrained.",
-        "type": "integer"
-      },
-      "scrollDelayMs": {
-        "default": 400,
-        "description": "Milliseconds to wait after each scroll for rendering to settle (default 400). Increase for slow/animated pages.",
-        "maximum": 3000,
-        "minimum": 100,
-        "type": "integer"
-      },
-      "windowTitle": {
-        "description": "Partial title of the window to capture (case-insensitive match)",
-        "type": "string"
-      }
-    },
-    "required": [
-      "action",
-      "windowTitle"
-    ],
-    "type": "object"
-  },
-  {
-    "additionalProperties": false,
-    "properties": {
-      "action": {
-        "const": "read"
-      },
-      "language": {
-        "description": "OCR language code (e.g. 'ja', 'en', 'zh'). Omit to auto-detect from Windows system locale via Intl.DateTimeFormat().resolvedOptions().locale. Default: auto.",
-        "type": "string"
-      },
-      "maxPages": {
-        "default": 20,
-        "description": "Maximum number of scroll steps / OCR pages (default 20, max 50).",
-        "maximum": 50,
-        "minimum": 1,
-        "type": "integer"
-      },
-      "scrollDelayMs": {
-        "default": 400,
-        "description": "Milliseconds to wait after each scroll for rendering to settle (default 400).",
-        "maximum": 3000,
-        "minimum": 100,
-        "type": "integer"
-      },
-      "scrollKey": {
-        "default": "PageDown",
-        "description": "Key sent to scroll one page. PageDown (default): full-page scroll for most apps. Space: web/PDF readers. ArrowDown: line-by-line slow scroll.",
-        "enum": [
-          "PageDown",
-          "Space",
-          "ArrowDown"
-        ],
-        "type": "string"
-      },
-      "stopWhenNoChange": {
-        "default": true,
-        "description": "Stop automatically when two consecutive pages yield no new lines after deduplication (page-end detection). Default true.",
-        "type": "boolean"
-      },
-      "windowTitle": {
-        "description": "Partial window title to focus and OCR (case-insensitive match).",
-        "type": "string"
-      }
-    },
-    "required": [
-      "action",
-      "windowTitle"
-    ],
-    "type": "object"
-  }
-]New value: +[
+  {
+    "additionalProperties": false,
+    "properties": {
+      "action": {
+        "const": "raw"
+      },
+      "amount": {
+        "default": 3,
+        "description": "Number of scroll steps (default 3)",
+        "type": "integer"
+      },
+      "direction": {
+        "description": "Scroll direction",
+        "enum": [
+          "up",
+          "down",
+          "left",
+          "right"
+        ],
+        "type": "string"
+      },
+      "homing": {
+        "default": true,
+        "description": "Apply window-movement homing correction to (x,y) before scrolling. Default true."
+      },
+      "hwnd": {
+        "description": "Direct window handle ID (takes precedence over windowTitle).",
+        "type": "string"
+      },
+      "include": {
+        "description": "Optional response-shape opt-in. `['envelope']` returns the self-documenting envelope (`_version` / `data` / `as_of` / `confidence`). `['raw']` forces raw shape (overrides DESKTOP_TOUCH_ENVELOPE=1 server default). Default behaviour is raw shape (compat with existing clients).",
+        "items": {
+          "type": "string"
+        },
+        "type": "array"
+      },
+      "speed": {
+        "description": "Cursor movement speed in px/sec (0=teleport, omit=default)",
+        "type": "number"
+      },
+      "windowTitle": {
+        "description": "Partial window title. When provided, the server focuses this window first.",
+        "type": "string"
+      },
+      "x": {
+        "description": "X coordinate to scroll at (moves cursor there first)",
+        "type": "number"
+      },
+      "y": {
+        "description": "Y coordinate to scroll at",
+        "type": "number"
+      }
+    },
+    "required": [
+      "action",
+      "direction"
+    ],
+    "type": "object"
+  },
+  {
+    "additionalProperties": false,
+    "properties": {
+      "action": {
+        "const": "to_element"
+      },
+      "block": {
+        "default": "center",
+        "description": "Vertical alignment after scroll — start/center/end/nearest (Chrome path only, default: center)",
+        "enum": [
+          "start",
+          "center",
+          "end",
+          "nearest"
+        ],
+        "type": "string"
+      },
+      "include": {
+        "description": "Optional response-shape opt-in. `['envelope']` returns the self-documenting envelope (`_version` / `data` / `as_of` / `confidence`). `['raw']` forces raw shape (overrides DESKTOP_TOUCH_ENVELOPE=1 server default). Default behaviour is raw shape (compat with existing clients).",
+        "items": {
+          "type": "string"
+        },
+        "type": "array"
+      },
+      "name": {
+        "description": "Partial name/label of the element (UIA name match). Use for native app elements. At least one of name or selector must be provided.",
+        "type": "string"
+      },
+      "port": {
+        "default": 9222,
+        "description": "CDP port for Chrome path (default 9222)",
+        "maximum": 65535,
+        "minimum": 1,
+        "type": "integer"
+      },
+      "selector": {
+        "description": "CSS selector for the element (Chrome/Edge only). At least one of name or selector must be provided.",
+        "type": "string"
+      },
+      "tabId": {
+        "description": "Tab ID (Chrome path only). Omit for first page tab.",
+        "type": "string"
+      },
+      "windowTitle": {
+        "description": "Partial window title (required for native path when name is used)",
+        "type": "string"
+      }
+    },
+    "required": [
+      "action"
+    ],
+    "type": "object"
+  },
+  {
+    "additionalProperties": false,
+    "properties": {
+      "action": {
+        "const": "smart"
+      },
+      "direction": {
+        "default": "into-view",
+        "description": "Scroll direction. into-view: scroll until target element is visible (default). Other values scroll unconditionally.",
+        "enum": [
+          "into-view",
+          "up",
+          "down",
+          "left",
+          "right"
+        ],
+        "type": "string"
+      },
+      "expandHidden": {
+        "default": false,
+        "description": "Temporarily set overflow:hidden ancestors to overflow:auto to unlock scroll. Mutates live CSS.",
+        "type": "boolean"
+      },
+      "hint": {
+        "description": "Scroll direction hint for binary-search (image path). Seeds lo/hi bounds to reduce attempts.",
+        "enum": [
+          "above",
+          "below",
+          "left",
+          "right"
+        ],
+        "type": "string"
+      },
+      "include": {
+        "description": "Optional response-shape opt-in. `['envelope']` returns the self-documenting envelope (`_version` / `data` / `as_of` / `confidence`). `['raw']` forces raw shape (overrides DESKTOP_TOUCH_ENVELOPE=1 server default). Default behaviour is raw shape (compat with existing clients).",
+        "items": {
+          "type": "string"
+        },
+        "type": "array"
+      },
+      "inline": {
+        "default": "center",
+        "description": "Vertical alignment after scroll (CDP path). Default: center.",
+        "enum": [
+          "start",
+          "center",
+          "end",
+          "nearest"
+        ],
+        "type": "string"
+      },
+      "maxDepth": {
+        "default": 3,
+        "description": "Max number of ancestor scroll containers to walk. Default 3.",
+        "maximum": 10,
+        "minimum": 1,
+        "type": "integer"
+      },
+      "port": {
+        "default": 9222,
+        "description": "CDP port (default 9222)",
+        "maximum": 65535,
+        "minimum": 1,
+        "type": "integer"
+      },
+      "retryCount": {
+        "default": 3,
+        "description": "Max scroll attempts (image path binary-search). Default 3, cap 4.",
+        "maximum": 4,
+        "minimum": 1,
+        "type": "integer"
+      },
+      "strategy": {
+        "default": "auto",
+        "description": "auto (default): try CDP → UIA → image in order. cdp: Chrome/Edge only. uia: native Windows UIA. image: image + Win32 binary-search.",
+        "enum": [
+          "auto",
+          "cdp",
+          "uia",
+          "image"
+        ],
+        "type": "string"
+      },
+      "tabId": {
+        "description": "CDP tab ID (Chrome path only). Omit for first page tab.",
+        "type": "string"
+      },
+      "target": {
+        "description": "CSS selector (Chrome/Edge) or partial UIA name (native apps). For CDP path, must be a valid CSS selector (starts with #, ., tag, or [ ). For UIA path, a partial name match against element Name property.",
+        "type": "string"
+      },
+      "verifyWithHash": {
+        "default": false,
+        "description": "Verify scroll effectiveness via perceptual hash comparison. Automatically enabled for image path.",
+        "type": "boolean"
+      },
+      "virtualIndex": {
+        "description": "Target row index in a virtualised list (0-based). Enables direct TanStack/data-index seeking.",
+        "minimum": 0,
+        "type": "integer"
+      },
+      "virtualTotal": {
+        "description": "Total row count in a virtualised list. Required when virtualIndex is set.",
+        "minimum": 1,
+        "type": "integer"
+      },
+      "windowTitle": {
+        "description": "Partial window title. Required for UIA and image paths. For CDP path, optional.",
+        "type": "string"
+      }
+    },
+    "required": [
+      "action",
+      "target"
+    ],
+    "type": "object"
+  },
+  {
+    "additionalProperties": false,
+    "properties": {
+      "action": {
+        "const": "capture"
+      },
+      "direction": {
+        "default": "down",
+        "description": "Scroll direction: 'down' (vertical, uses Page Down key) or 'right' (horizontal, uses mouse scroll). Default 'down'.",
+        "enum": [
+          "down",
+          "right"
+        ],
+        "type": "string"
+      },
+      "include": {
+        "description": "Optional response-shape opt-in. `['envelope']` returns the self-documenting envelope (`_version` / `data` / `as_of` / `confidence`). `['raw']` forces raw shape (overrides DESKTOP_TOUCH_ENVELOPE=1 server default). Default behaviour is raw shape (compat with existing clients).",
+        "items": {
+          "type": "string"
+        },
+        "type": "array"
+      },
+      "maxScrolls": {
+        "default": 10,
+        "description": "Maximum scroll iterations before stopping (default 10, max 30)",
+        "maximum": 30,
+        "minimum": 1,
+        "type": "integer"
+      },
+      "maxWidth": {
+        "default": 1280,
+        "description": "Max size of the short edge of the final image (default 1280). For 'down': caps the image width; height is unconstrained. For 'right': caps the image height; width is unconstrained.",
+        "type": "integer"
+      },
+      "scrollDelayMs": {
+        "default": 400,
+        "description": "Milliseconds to wait after each scroll for rendering to settle (default 400). Increase for slow/animated pages.",
+        "maximum": 3000,
+        "minimum": 100,
+        "type": "integer"
+      },
+      "windowTitle": {
+        "description": "Partial title of the window to capture (case-insensitive match)",
+        "type": "string"
+      }
+    },
+    "required": [
+      "action",
+      "windowTitle"
+    ],
+    "type": "object"
+  },
+  {
+    "additionalProperties": false,
+    "properties": {
+      "action": {
+        "const": "read"
+      },
+      "include": {
+        "description": "Optional response-shape opt-in. `['envelope']` returns the self-documenting envelope (`_version` / `data` / `as_of` / `confidence`). `['raw']` forces raw shape (overrides DESKTOP_TOUCH_ENVELOPE=1 server default). Default behaviour is raw shape (compat with existing clients).",
+        "items": {
+          "type": "string"
+        },
+        "type": "array"
+      },
+      "language": {
+        "description": "OCR language code (e.g. 'ja', 'en', 'zh'). Omit to auto-detect from Windows system locale via Intl.DateTimeFormat().resolvedOptions().locale. Default: auto.",
+        "type": "string"
+      },
+      "maxPages": {
+        "default": 20,
+        "description": "Maximum number of scroll steps / OCR pages (default 20, max 50).",
+        "maximum": 50,
+        "minimum": 1,
+        "type": "integer"
+      },
+      "scrollDelayMs": {
+        "default": 400,
+        "description": "Milliseconds to wait after each scroll for rendering to settle (default 400).",
+        "maximum": 3000,
+        "minimum": 100,
+        "type": "integer"
+      },
+      "scrollKey": {
+        "default": "PageDown",
+        "description": "Key sent to scroll one page. PageDown (default): full-page scroll for most apps. Space: web/PDF readers. ArrowDown: line-by-line slow scroll.",
+        "enum": [
+          "PageDown",
+          "Space",
+          "ArrowDown"
+        ],
+        "type": "string"
+      },
+      "stopWhenNoChange": {
+        "default": true,
+        "description": "Stop automatically when two consecutive pages yield no new lines after deduplication (page-end detection). Default true.",
+        "type": "boolean"
+      },
+      "windowTitle": {
+        "description": "Partial window title to focus and OCR (case-insensitive match).",
+        "type": "string"
+      }
+    },
+    "required": [
+      "action",
+      "windowTitle"
+    ],
+    "type": "object"
+  }
+]

Addedv1.1.1Apr 28, 2026
Removedv1.1.0Apr 27, 2026
Addedv1.0.3Apr 26, 2026
Removedv0.15.7Apr 20, 2026

Changed1 schema field changedv0.15.4Apr 19, 2026

addedInput schema / properties / hwnd

Added value: +{
+  "description": "Direct window handle ID (takes precedence over windowTitle). Obtain from get_windows response (hwnd field). String type to avoid 64-bit precision issues.",
+  "type": "string"
+}

Changed11 schema fields changedv0.10.0Apr 16, 2026

removedInput schema / $schema

Removed value: -"http://json-schema.org/draft-07/schema#"

addedInput schema / additionalProperties
```
Added value: +false
```

removedInput schema / properties / _stub

Removed value: -{
-  "description": "Stub tool — arguments ignored."
-}

addedInput schema / properties / amount

Added value: +{
+  "default": 3,
+  "description": "Number of scroll steps (default 3)",
+  "type": "integer"
+}

addedInput schema / properties / direction

Added value: +{
+  "description": "Scroll direction",
+  "enum": [
+    "up",
+    "down",
+    "left",
+    "right"
+  ],
+  "type": "string"
+}

addedInput schema / properties / homing

Added value: +{
+  "default": true,
+  "description": "Enable homing correction if the target window moved.",
+  "type": "boolean"
+}

addedInput schema / properties / speed

Added value: +{
+  "description": "Cursor movement speed in px/sec. 0 = instant.",
+  "minimum": 0,
+  "type": "integer"
+}

addedInput schema / properties / windowTitle

Added value: +{
+  "description": "Partial title of the target window.",
+  "type": "string"
+}

addedInput schema / properties / x

Added value: +{
+  "description": "X coordinate to scroll at (moves cursor there first)",
+  "type": "number"
+}

addedInput schema / properties / y

Added value: +{
+  "description": "Y coordinate to scroll at",
+  "type": "number"
+}

addedInput schema / required
```
Added value: +[
+  "direction"
+]
```

First observedv0.6.2Apr 14, 2026

TDQS

A4.8/5.0

Behavior5/5

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

With no annotations provided, the description carries the full burden and delivers extensively: it discloses pixel-vs-screen-coordinate mismatch for capture, the mutating CSS side effect of expandHidden, OCR accuracy limits, the requirement for window visibility in read mode, typed error codes (ScrollNotDelivered, OverflowHiddenAncestor, VirtualScrollExhausted), and the weak-evidence caveat for verifyDelivery pixel_delta_observed. It also explains the wheel-notch semantics and the 1000-notch ceiling rationale.

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 long but densely packed with high-value information, organized into Purpose, Details, Prefer, Caveats, and Examples sections. It front-loads the five strategies and their one-line definitions before diving into per-action details. The length is justified by the tool's complexity (5 modes, 32 parameters), though a few details (e.g., ADR-018 §2.6 reference) are terse to the point of being cryptic for an agent.

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?

For a 32-parameter, 5-mode tool with no output schema and no annotations, the description is remarkably complete. It covers per-action semantics, error codes, prerequisites (browser_open for CDP, UIA ScrollItemPattern for native), fallback ordering, and even provides five usage examples covering different actions. The only minor gap is that the return shape for each action is not explicitly described, but the description's examples and caveats largely compensate.

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%, so the baseline is 3. The description adds substantial meaning beyond the schema: it explains the relationship between amount and screenfuls, clarifies that one notch equals one physical wheel detent, gives per-app step sizes, and explains per-action required fields are enforced at call time. It also adds context for parameters like sizeReduced (mentioned in description though not in schema) and virtualIndex/virtualTotal via the VirtualScrollExhausted error. Minor deduction because the description is not exhaustive for every parameter (e.g., homing, scrollKey, verifyWithHash are only in 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 opens with a clear verb and resource ('Scroll a window or page') and immediately enumerates the five action strategies with one-line definitions. It distinguishes itself from siblings like mouse_click, browser_eval, and screenshot by naming its own sub-modes (raw, to_element, smart, capture, read) and their outputs.

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?

The 'Prefer' section explicitly states when to use each action and when not to: use to_element/smart for entity_outside_viewport recovery, use capture for reading long pages as images, use read for OCR text extraction, and use raw for simple scrolling. It also names alternatives (focus_window, desktop_discover, browser_eval, browser_overview) and gives exclusion conditions like 'scrolling only helps when the target scrolled out of its own window'.

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

scroll

Instructions

Input Schema

Schema Changelog

TDQS

Other Tools