desktop-touch-mcp

日本語

Beyond Coordinate Roulette: LLM-native Windows automation with a Semantic World-Graph and Auto-Perception.

An MCP server that gives Claude eyes and hands on Windows. It moves beyond pixel-guessing by grounding all interactions in a Semantic World-Graph (desktop_discover) and verifying every action with Auto-Perception guards. Optimized into 28 high-signal tools covering screenshots, background input (WM_CHAR), UIA, Chrome CDP, terminal, and token-efficient P-frame diffing.

v0.15: 82× average speedup via Rust native engine — UIA focus queries in 2 ms, SSE2-accelerated image diffing at 13–15× native speed. Zero-config: the engine auto-loads when present, with transparent PowerShell fallback. v0.15.5: Pinned release verification — the npm launcher now fetches only the matching GitHub Release tag and verifies the Windows runtime zip before extraction.

---

Features

• ⚡ High-performance Rust Native Core — The UIA bridge and image-diff engine are written in Rust (napi-rs + windows-rs) and loaded as a native .node addon. Direct COM calls from a dedicated MTA thread eliminate PowerShell process spawning — getFocusedElement completes in 2 ms (160× faster), and getUiElements returns full trees in ~100 ms with a batch BFS algorithm that minimizes cross-process RPC. Image-diff operations use SSE2 SIMD for 13–15× throughput. When the native engine is unavailable, every function transparently falls back to PowerShell — zero config required.
• 🎯 Set-of-Marks (SoM) visual fallback — Games, RDP sessions, and non-accessible Electron apps return clickable elements even when UIA is completely blind. screenshot(detail="text") automatically detects UIA sparsity and activates a Hybrid Non-CDP pipeline: Rust-powered grayscale + bilinear upscale → Windows OCR → clustering → red bounding-box annotation with numbered badges ([1], [2]…). Two parallel representations returned: a visual PNG for spatial orientation and a semantic elements[] list with clickAt coords — no CDP required.
• LLM-native design — Built around how LLMs think, not how humans click. run_macro batches multiple operations into a single API call; diffMode sends only the windows that changed since the last frame. Minimal tokens, minimal round-trips.
• Reactive Perception Graph — Register a lensId for a window or browser tab, pass it to action tools, and get guard-checked post.perception feedback after each action. It reduces repeated screenshot / desktop_state calls and prevents wrong-window typing or stale-coordinate clicks.
• Full CJK support — Uses Win32 GetWindowTextW for window titles, avoiding nut-js garbling. IME bypass input supported for Japanese/Chinese/Korean environments.
• 3-tier token reduction — detail="image" (~443 tok) / detail="text" (~100–300 tok) / diffMode=true (~160 tok). Send pixels only when you actually need to see them.
• 1:1 coordinate mode — dotByDot=true captures at native resolution (WebP). Image pixel = screen coordinate — no scale math needed. With origin+scale passed to mouse_click, the server converts coords for you — eliminating off-by-one / scale bugs.
• Browser capture data reduction — grayscale=true (~50% size), dotByDotMaxDimension=1280 (auto-scaled with coord preservation), and windowTitle + region sub-crops help exclude browser chrome and other irrelevant pixels. Typical reduction for heavy captures: 50–70%.
• Chromium smart fallback — detail="text" on Chrome/Edge/Brave auto-skips UIA (prohibitively slow there) and runs Windows OCR. hints.chromiumGuard + hints.ocrFallbackFired flag the path taken.
• UIA element extraction — detail="text" returns button names and clickAt coords as JSON. Claude can click the right element without ever looking at a screenshot.
• Auto-dock CLI — window_dock(action='dock') snaps any window to a screen corner with always-on-top. Set DESKTOP_TOUCH_DOCK_TITLE='@parent' to auto-dock the terminal hosting Claude on MCP startup — the process-tree walker finds the right window regardless of title.
• Emergency stop (Failsafe) — Move the mouse to the top-left corner (within 10px of 0,0) to immediately terminate the MCP server.

---

Requirements

OS	Windows 10 / 11 (64-bit)
Node.js	v20+ recommended (tested on v22+)
PowerShell	5.1+ (bundled with Windows) — used only as fallback when the Rust native engine is unavailable
Claude CLI	claude command must be available

Note: nut-js native bindings require the Visual C++ Redistributable. Download from Microsoft if not already installed.

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Installation

npx -y @harusame64/desktop-touch-mcp

The npm launcher resolves runtime strictly by npm package version. For package X.Y.Z, it fetches only GitHub Release tag vX.Y.Z, downloads desktop-touch-mcp-windows.zip, verifies its SHA256 digest, and only then expands it under %USERPROFILE%\.desktop-touch-mcp. Verified cached releases are reused on later runs.

Set DESKTOP_TOUCH_MCP_HOME to override the cache root directory.

Register with Claude CLI

Add to ~/.claude.json under mcpServers:

{
  "mcpServers": {
    "desktop-touch": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "@harusame64/desktop-touch-mcp"]
    }
  }
}

No system prompt needed. The command reference is automatically injected into Claude via the MCP initialize response's instructions field.

Register with other clients (HTTP mode)

Clients that require an HTTP endpoint (GPT Desktop, VS Code Copilot, Cursor, etc.) can use the built-in Streamable HTTP transport:

npx -y @harusame64/desktop-touch-mcp --http
# or with a custom port:
npx -y @harusame64/desktop-touch-mcp --http --port 8080

The server starts at http://127.0.0.1:23847/mcp (localhost only). Register the URL in your MCP client settings. A health check is available at http://127.0.0.1:<port>/health.

In HTTP mode the system tray icon shows the active URL and provides quick-copy and open-in-browser shortcuts.

Development install

git clone https://github.com/Harusame64/desktop-touch-mcp.git
cd desktop-touch-mcp
npm install

Build after install:

npm run build

For a local checkout, register the built server directly:

{
  "mcpServers": {
    "desktop-touch": {
      "type": "stdio",
      "command": "node",
      "args": ["D:/path/to/desktop-touch-mcp/dist/index.js"]
    }
  }
}

Note: Replace D:/path/to/desktop-touch-mcp with the actual path where you cloned this repository.

---

Tools (28 Optimized Tools)

📖 Full Reference: docs/system-overview.md — Exhaustive guide on parameters, return schemas, and coordinate math.

🌐 World-Graph V2 (Primary Path)

Tool	Description
desktop_discover	Observe the desktop. Returns interactive entities with leases (UIA, CDP, Terminal, Visual SoM).
desktop_act	Perform actions (click, type, drag, select) on entities via lease validation. Returns semantic diffs.

👁️ Observation & State

Tool	Description
desktop_state	Lightweight check of focus, active window, cursor, and Auto-Perception attention signal.
screenshot	Multi-mode capture: detail='text' (UIA/OCR), diffMode (P-frame), dotByDot (1:1), and background.
workspace_snapshot	Instant session orientation: all window thumbnails + UI summaries in one call.
server_status	Diagnostic check for native engine health and feature activation.

⌨️ Input & Control

Tool	Description
keyboard	Send keyboard input. Supports background input (WM_CHAR) and IME-safe clipboard bypass.
mouse_click / mouse_drag	Precision coordinate-based interaction with homing and force-focus protection.
scroll	Multi-strategy: raw (notches), to_element, smart (virtual lists), and capture (stitch).
click_element	Legacy UIA-based click by name/ID (fallback when entities are unavailable).

🌐 Browser CDP (Chrome/Edge/Brave)

Tool	Description
browser_open / browser_navigate	Idempotent debug-mode launch and reliable navigation.
browser_click / browser_fill / browser_form	High-level DOM interaction stable across repaints and framework re-renders.
browser_eval	Deep inspection via js (scripting), dom (HTML), and appState (SPA data extraction).
browser_overview / browser_search / browser_locate	Semantic discovery, grep-like DOM search, and pixel-accurate coordinate lookup.

🛠️ Utilities & Workflow

Tool	Description
terminal	Unified command execution: run (send + wait + read), read (OCR/UIA), and send.
wait_until	Efficient server-side polling for window, focus, text, or URL state changes.
window_dock / focus_window	Window management: pin (always-on-top), unpin, dock (corner snap), and focus.
workspace_launch	Launch apps and auto-detect new HWNDs (supports localized titles).
run_macro	Batch up to 50 operations into a single round-trip for maximum efficiency.
clipboard / notification_show	System-level text exchange and user alerts.

---

Standard workflow (v1.0.0)

The v2 World-Graph surface (desktop_discover / desktop_act) is the recommended dispatch path. The four-call shape works for native apps, browsers, and terminals identically.

desktop_state          → orient: focused window/element, modal, attention signal
desktop_discover       → find actionable entities (returns lease + windows[])
desktop_act(lease, …)  → act on entity (returns attention + post.perception)
desktop_state          → confirm the world changed as expected

Clicking — priority order:

browser_click(selector)               → Chrome / Edge (CDP, stable across repaints)
desktop_act(lease, action='click')    → native / dialog / visual (entity-based; use after desktop_discover)
click_element(name | automationId)    → native UIA fallback if desktop_act returns ok:false
mouse_click(x, y, origin?, scale?)    → pixel last resort; origin+scale from dotByDot screenshots only

Recovery hints — read response.attention after every observation and response.warnings[] on desktop_discover / desktop_act. Common reasons:

• lease_expired / lease_generation_mismatch / lease_digest_mismatch / entity_not_found → re-call desktop_discover
• modal_blocking → response.blockingElement (when present) names the blocking modal; dismiss via click_element(name=blockingElement.name) then retry
• entity_outside_viewport → scroll(action='to_element' | 'raw'), then re-call desktop_discover
• executor_failed → fall back to click_element / mouse_click / browser_click

Lease lifecycle:

• Each desktop_discover response carries softExpiresAtMs (≈ 60 % of the TTL window). Past that timestamp the LLM should consider re-calling desktop_discover even though the lease is still technically valid — lease.expiresAtMs is the only correctness wall.
• TTL adapts to view mode (action/explore/debug), entity count, and response payload size. Cap is 60 s.
• Set DESKTOP_TOUCH_DISABLE_FUKUWARAI_V2=1 to fall back to the v1 tool surface (get_windows / get_ui_elements / set_element_value) for troubleshooting only — V2 is the recommended default.

---

Browser CDP automation

For web automation, connect Chrome or Edge with the remote debugging port enabled — no Selenium or Playwright needed.

# Launch Chrome in CDP mode
chrome.exe --remote-debugging-port=9222 --user-data-dir=C:\tmp\cdp

browser_open({launch:{}})                          → spawn-if-needed Chrome in debug mode + list tabs (idempotent)
browser_open()                                     → connect-only (fail if no CDP endpoint live)
browser_locate({selector:"#submit"})               → CSS selector → physical screen coords
browser_click({selector:"#submit"})                → find + click in one step (auto-focuses browser)
browser_eval({action:"js", expression:"document.title"})  → evaluate JS, returns result
browser_eval({action:"dom", selector:"#main", maxLength:5000})  → outerHTML, truncated to maxLength chars
browser_eval({action:"appState"})                  → one-shot SPA state (Next/Nuxt/Remix/Apollo/GitHub react-app/Redux SSR)
browser_fill({selector:"#email", value:"user@example.com"})  → fill React/Vue/Svelte controlled input (state-safe)
browser_overview()                                 → links/buttons/inputs + ARIA toggles + viewportPosition per element
browser_search({by:"text", pattern:"..."})         → grep DOM with confidence ranking
browser_navigate({url:"https://example.com"})      → navigate via CDP (no address bar interaction)

For chained calls in the same tab, pass includeContext:false to omit the activeTab/readyState annotation (~150 tok/call saved). Boolean / object params accept the LLM-friendly string spellings ("true", "{}").

Coordinates returned by browser_locate account for the browser chrome (tab strip + address bar height) and devicePixelRatio, so they can be passed directly to mouse_click without any scaling.

Recommended web workflow:

browser_open({launch:{}}) → browser_eval({action:"dom"}) → browser_locate(selector) → browser_click(selector)

---

Auto-dock CLI on startup

Keep Claude CLI visible while operating other apps full-screen. Set env vars in your MCP config and the docked window auto-snaps into place every MCP startup.

{
  "mcpServers": {
    "desktop-touch": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "@harusame64/desktop-touch-mcp"],
      "env": {
        "DESKTOP_TOUCH_DOCK_TITLE": "@parent",
        "DESKTOP_TOUCH_DOCK_CORNER": "bottom-right",
        "DESKTOP_TOUCH_DOCK_WIDTH": "480",
        "DESKTOP_TOUCH_DOCK_HEIGHT": "360",
        "DESKTOP_TOUCH_DOCK_PIN": "true"
      }
    }
  }
}

Env var	Default	Notes
DESKTOP_TOUCH_DOCK_TITLE	(unset = off)	@parent walks the MCP process tree to find the hosting terminal — immune to title / branch / project changes. Or use a literal substring.
DESKTOP_TOUCH_DOCK_CORNER	bottom-right	top-left / top-right / bottom-left / bottom-right
DESKTOP_TOUCH_DOCK_WIDTH / HEIGHT	480 / 360	px ("480") or ratio of work area ("25%") — 4K/8K auto-adapts
DESKTOP_TOUCH_DOCK_PIN	true	Always-on-top toggle
DESKTOP_TOUCH_DOCK_MONITOR	primary	Monitor id from desktop_state({includeScreen:true})
DESKTOP_TOUCH_DOCK_SCALE_DPI	false	If true, multiply px values by dpi / 96 (opt-in per-monitor scaling)
DESKTOP_TOUCH_DOCK_MARGIN	8	Screen-edge padding (px)
DESKTOP_TOUCH_DOCK_TIMEOUT_MS	5000	Max wait for the target window to appear

Input routing gotcha: when a pinned window is active (e.g. Claude CLI), keyboard(action='type') / keyboard(action='press') send keys to it, not the app you wanted to type into. Always call focus_window(title=...) before keyboard operations, then verify isActive=true via screenshot(detail='meta').

Auto Perception (always-on)

Phase 4 privatizes the explicit perception_* tool family — the v0.12 Auto Perception layer attaches an attention signal to every desktop_state and desktop_act response automatically. Action tools also auto-guard when given a windowTitle. There is no longer a need to register / read / forget lenses manually.

# desktop_state always returns the attention signal
desktop_state() → {focusedWindow, focusedElement, modal, attention:"ok", ...}

# Action tools auto-guard when windowTitle is given:
keyboard({action:"type", text:"hello", windowTitle:"Notepad"})
→ post.perception:{status:"ok"}  // unsafe input blocked if guards fail

# When attention is dirty / stale / settling, refresh with desktop_state:
desktop_state()  // re-evaluates attention via Auto Perception

For advanced pinned-target workflows, the lensId parameter remains on action tools (keyboard, mouse_click, mouse_drag, click_element, browser_click, browser_navigate, browser_eval, desktop_act). Omit lensId for the normal Auto Perception path. The underlying registry, hot target cache, and sensor loop are unchanged; only the explicit perception_register / perception_read / perception_forget / perception_list tools were retired.

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Mouse homing correction

When Claude calls screenshot(detail='text') to read coordinates and then mouse_click seconds later, the target window may have moved. The homing system corrects this automatically.

Tier	How to enable	Latency	What it does
1	Always-on (if cache exists)	<1ms	Applies (dx, dy) offset when window moved
2	Pass windowTitle hint	~100ms	Auto-focuses window if it went behind another
3	Pass elementName/elementId + windowTitle	1–3s	UIA re-query for fresh coords on resize

# Tier 1 only (automatic)
mouse_click(x=500, y=300)

# Tier 1 + 2: also bring window to front if hidden
mouse_click(x=500, y=300, windowTitle="Notepad")

# Tier 1 + 2 + 3: also re-query UIA if window resized
mouse_click(x=500, y=300, windowTitle="Notepad", elementName="Save")

# Traction control OFF — no correction
mouse_click(x=500, y=300, homing=false)

The homing parameter is available on mouse_click, mouse_drag, and scroll. The cache is updated automatically on every screenshot(), desktop_discover(), focus_window(), and workspace_snapshot() call.

mouse_click image-local coords (origin + scale)

When you take a dotByDot screenshot with dotByDotMaxDimension, the response prints the origin and scale values. Instead of computing screen coords manually, copy them into mouse_click:

# Screenshot response:
#   origin: (0, 120) | scale: 0.6667
#   To click image pixel (ix, iy): mouse_click(x=ix, y=iy, origin={x:0, y:120}, scale=0.6667)

mouse_click(x=640, y=300, origin={x:0, y:120}, scale=0.6667, windowTitle="Chrome")
# Server converts: screen = (0 + 640/0.6667, 120 + 300/0.6667) = (960, 570)

This eliminates a whole class of off-by-one and scale bugs. Without origin/scale, x/y remain absolute screen pixels (unchanged behavior).

---

screenshot key parameters

detail="image"          — PNG/WebP pixels (default)
detail="text"           — UIA element JSON + clickAt coords (no image, ~100–300 tok)
detail="meta"           — Title + region only (cheapest, ~20 tok/window)
dotByDot=true           — 1:1 WebP; image_px + origin = screen_px
dotByDotMaxDimension=N  — cap longest edge (response includes scale for coord math)
grayscale=true          — ~50% smaller for text-heavy captures (code/AWS console)
region={x,y,w,h}        — with windowTitle: window-local coords (exclude browser chrome)
                          without: virtual screen coords
diffMode=true           — I-frame first call, P-frame (changed windows only) after (~160 tok)
ocrFallback="auto"      — detail='text' auto-fires Windows OCR on uiaSparse or empty

Recommended Chrome combo (50–70% data reduction):

screenshot(windowTitle="Chrome",
           dotByDot=true, dotByDotMaxDimension=1280, grayscale=true,
           region={x:0, y:120, width:1920, height:900})  # skip browser chrome

Recommended workflow:

workspace_snapshot()                     → full orientation (resets diff buffer)
screenshot(detail="text", windowTitle=X) → get actionable[].clickAt coords
mouse_click(x, y)                        → click directly, no math needed
screenshot(diffMode=true)                → check only what changed (~160 tok)

---

Security

Emergency stop (Failsafe)

Move the mouse to the top-left corner of the screen (within 10px of 0,0) to immediately terminate the MCP server.

• Per-tool check: checkFailsafe() runs before every tool handler
• Background monitor: 500ms polling as a backup for long-running operations
• Trigger radius: 10px

Blocked operations

workspace_launch blocklist: cmd.exe, powershell.exe, pwsh.exe, wscript.exe, cscript.exe, mshta.exe, regsvr32.exe, rundll32.exe, msiexec.exe, bash.exe, wsl.exe are blocked. Script extensions (.bat, .ps1, .vbs, etc.) are rejected. Arguments containing ;, &, |, `, $(, ${ are also rejected.

keyboard(action='press') blocklist: Win+R (Run dialog), Win+X (admin menu), Win+S (search), Win+L (lock screen) are blocked.

PowerShell injection protection

All -like patterns in the UIA bridge PowerShell fallback path are sanitized with escapeLike(), which escapes wildcard characters (*, ?, [, ]) before they reach PowerShell. When the Rust native engine is active, PowerShell is not invoked for UIA operations.

Allowlist for workspace_launch

Shell interpreters are blocked by default. To allow specific executables, create an allowlist file:

File locations (searched in order):

1. Path in DESKTOP_TOUCH_ALLOWLIST environment variable
2. ~/.claude/desktop-touch-allowlist.json
3. desktop-touch-allowlist.json in the server's working directory

Format:

{
  "allowedExecutables": [
    "pwsh.exe",
    "C:\\Tools\\myapp.exe"
  ]
}

Changes take effect immediately — no restart needed.

---

Mouse movement speed

All mouse tools (mouse_click, mouse_drag, scroll) accept an optional speed parameter:

Value	Behavior
Omitted	Uses the configured default (see below)
0	Instant teleport — setPosition(), no animation
1–N	Animated movement at N px/sec

Default speed is 1500 px/sec. Change it permanently via the DESKTOP_TOUCH_MOUSE_SPEED environment variable:

{
  "mcpServers": {
    "desktop-touch": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "@harusame64/desktop-touch-mcp"],
      "env": {
        "DESKTOP_TOUCH_MOUSE_SPEED": "3000"
      }
    }
  }
}

Common values: 0 = teleport, 1500 = default gentle, 3000 = fast, 5000 = very fast.

---

Force-Focus (AttachThreadInput)

Windows foreground-stealing protection can prevent SetForegroundWindow from succeeding when another window (such as a pinned Claude CLI) is in the foreground. This causes subsequent keystrokes or clicks to land in the wrong window — a silent failure.

mouse_click, keyboard(action='type'), keyboard(action='press'), and terminal(action='send') all accept a forceFocus parameter that bypasses this protection using AttachThreadInput:

{
  "name": "mouse_click",
  "arguments": {
    "x": 500,
    "y": 300,
    "windowTitle": "Google Chrome",
    "forceFocus": true
  }
}

If the force attempt is refused despite AttachThreadInput, the response includes hints.warnings: ["ForceFocusRefused"].

Global default via environment variable:

{
  "mcpServers": {
    "desktop-touch": {
      "env": {
        "DESKTOP_TOUCH_FORCE_FOCUS": "1"
      }
    }
  }
}

Setting DESKTOP_TOUCH_FORCE_FOCUS=1 makes forceFocus: true the default for all four tools without changing each call.

Known tradeoffs:

• During the ~10ms AttachThreadInput window, key state and mouse capture are shared between the two threads. In rapid macro sequences this can cause a race condition (rare in practice).
• Disable forceFocus (or unset the env var) when the user is manually operating another app to avoid unexpected focus shifts.

---

Auto Guard (v0.12+)

Action tools (mouse_click, mouse_drag, keyboard(action='type'/'press'), click_element, desktop_act, browser_click, browser_navigate) automatically guard each action when you pass windowTitle / tabId:

• Verifies target window identity (process restart / HWND replacement detected)
• Confirms click coordinates are inside the target window rect
• Returns post.perception.status on every response — including failures — so the LLM can recover without a screenshot

Disabling auto guard — set DESKTOP_TOUCH_AUTO_GUARD=0 to restore v0.11.12 behavior (no auto guard):

{
  "mcpServers": {
    "desktop-touch": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "@harusame64/desktop-touch-mcp"],
      "env": {
        "DESKTOP_TOUCH_AUTO_GUARD": "0"
      }
    }
  }
}

When auto guard is enabled (default), post.perception.status will be one of:

Status	Meaning
ok	Guard passed — target verified
unguarded	windowTitle not provided; action ran without guard
target_not_found	No window matched the given title
ambiguous_target	Multiple windows matched; use a more specific title
identity_changed	Window was replaced (process restart / HWND change)
unsafe_coordinates	Click coordinates are outside the target window rect
needs_escalation	Use browser_click or specify windowTitle

When unsafe_coordinates or identity_changed is returned, the response may include a suggestedFix.fixId. Pass that fixId to the relevant tool call to approve the recovery:

{ "name": "mouse_click",           "arguments": { "fixId": "fix-..." } }
{ "name": "keyboard(action='type')",         "arguments": { "fixId": "fix-...", "text": "hello" } }
{ "name": "click_element",         "arguments": { "fixId": "fix-..." } }
{ "name": "browser_click", "arguments": { "fixId": "fix-..." } }

The fix is one-shot and expires in 15 seconds. The server revalidates the target process identity before executing.

---

v0.13 Additions

Target-Identity Timeline

The server tracks a semantic timeline of what happened to each target window/tab. Recent events are included in:

• get_history → recentTargetKeys: array of 3 most recently active target keys (compact, no event bodies)
• perception_read(lensId) → recentEvents: up to 10 events for that lens's target, each with tsMs, semantic, summary

Enable the MCP resources below to browse timelines:

{ "env": { "DESKTOP_TOUCH_PERCEPTION_RESOURCES": "1" } }

MCP resources available when enabled:

URI	Content
perception://target/{targetKey}/timeline	Semantic event timeline for a target
perception://targets/recent	Most recently active target keys
perception://lens/{lensId}/summary	Lens attention/guard state

Manual Lens Eviction: FIFO → LRU

Manual lenses (created via perception_register) are now evicted by least-recently-used instead of insertion order. Using perception_read, evaluatePreToolGuards, or buildEnvelopeFor on a lens promotes it. The hard limit of 16 active lenses is unchanged.

browser_eval Structured Mode

Pass withPerception: true to receive a structured JSON response with post.perception instead of raw text:

{ "name": "browser_eval", "arguments": { "expression": "document.title", "withPerception": true } }

Returns { ok: true, result: "...", post: { perception: { status: "ok", ... } } }.

mouse_drag Cross-Window Guard

mouse_drag now guards both start and end coordinates. Drags that cross window boundaries (or reach the desktop wallpaper) are blocked by default. To allow intentional cross-window or range-selection drags:

{ "name": "mouse_drag", "arguments": { "startX": 100, "startY": 100, "endX": 900, "endY": 900, "allowCrossWindowDrag": true } }

---

Performance (v0.15 — Rust Native Engine)

The Rust native engine (@harusame64/desktop-touch-engine) replaces PowerShell process spawning with direct COM calls over a persistent MTA thread. It loads automatically as a .node addon — no configuration needed.

UIA Benchmark (vs PowerShell baseline)

Function	Rust Native	PowerShell	Speedup
getFocusedElement	2.2 ms	366 ms	163.9×
getUiElements (Explorer, ~60 elements)	106.5 ms	346 ms	3.3×
Weighted average			~82×

Image Diff Benchmark (SSE2 SIMD)

Function	Rust (SSE2)	TypeScript	Speedup
computeChangeFraction (1920×1080)	0.26 ms	3.8 ms	~15×
dHash (perceptual hash)	0.09 ms	1.2 ms	~13×

Architecture

Claude CLI / MCP Client
    │  stdio or HTTP (MCP protocol)
    ▼
desktop-touch-mcp (TypeScript)
    │
    ├── Rust Native Engine (.node addon)          ← NEW in v0.15
    │   ├── UIA: 13 functions via napi-rs + windows-rs 0.62
    │   │   └── Dedicated COM thread (MTA) + batch BFS algorithm
    │   └── Image: SSE2 SIMD pixel diff + perceptual hashing
    │
    └── PowerShell Fallback (automatic)
        └── Activates transparently if .node is unavailable

Why getUiElements is 3.3× (not 160×)

The 160× speedup on getFocusedElement comes from eliminating PowerShell process startup (~200 ms) and .NET assembly loading. For getUiElements, the bottleneck shifts to the UIA provider inside the target application (e.g., Explorer) — it must enumerate its UI tree regardless of who asks. The Rust engine uses a batch BFS algorithm (FindAllBuildCache + TreeScope_Children) that minimizes cross-process RPC calls and supports maxElements early exit, making it dramatically faster on large trees (VS Code, browsers with 1000+ elements).

---

UI Operating Layer (V2)

Status: Default ON since v0.17. desktop_discover and desktop_act are available out of the box.

V2 introduces two new tools that replace coordinate-based clicking with entity-based interaction:

Tool	Description
desktop_discover	Observe a window or browser tab. Returns interactive entities with leases — no raw screen coordinates. Supports UIA (native), CDP (browser), terminal, and visual GPU lanes.
desktop_act	Interact with an entity returned by desktop_discover. Validates the lease before executing. Returns a semantic diff (entity_disappeared, modal_appeared, focus_shifted, …).

Clicking — priority order

When multiple tools could perform the same click, prefer them in this order:

1. browser_click(selector) — Chrome / Edge over CDP (stable across repaints)
2. desktop_act(lease) — native windows, dialogs, visual-only targets (entity-based; use after desktop_discover)
3. click_element(name | automationId) — native UIA fallback when desktop_act returns ok:false
4. mouse_click(x, y) — pixel-level last resort (origin + scale from dotByDot screenshots only)

Disabling V2 (kill switch)

To hide desktop_discover / desktop_act from the tool catalog, add the disable flag and restart:

{
  "mcpServers": {
    "desktop-touch": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "@harusame64/desktop-touch-mcp"],
      "env": {
        "DESKTOP_TOUCH_DISABLE_FUKUWARAI_V2": "1"
      }
    }
  }
}

All V1 tools continue to work without interruption — no reinstall required. Remove the env entry and restart to re-enable.

Flag semantics (exact-match: only the literal string "1" counts):

DISABLE_FUKUWARAI_V2	ENABLE_FUKUWARAI_V2	V2 state
unset / not "1"	unset / not "1"	ON (default)
unset / not "1"	"1"	ON (legacy flag — see below)
"1"	any	OFF — DISABLE wins

Deprecated: DESKTOP_TOUCH_ENABLE_FUKUWARAI_V2

This was the opt-in switch in v0.16.x. From v0.17 it is accepted for compatibility but no longer required — the server prints a deprecation warning on startup when it is set. It will be removed in v0.18. Remove it from your config when you upgrade.

Recovery when V2 fails

If desktop_act returns ok: false, read reason and follow the built-in recovery hints in the tool description. Common paths:

• lease_expired / *_mismatch / entity_not_found → re-call desktop_discover
• modal_blocking → response.blockingElement (when present) carries { name, role, automationId? }; dismiss with click_element(name=blockingElement.name), then retry
• entity_outside_viewport → scroll / scroll(action='to_element'), then re-call desktop_discover
• executor_failed → fall back to click_element / mouse_click / browser_click

For desktop_discover warnings (visual_provider_unavailable, visual_provider_warming, cdp_provider_failed, …), V1 tools (screenshot, click_element, get_ui_elements, terminal(action='send'), …) remain available as an escape hatch.

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Known limitations

Limitation	Detail	Workaround
Games / video players may return black or hang in background capture	DirectX fullscreen apps may not work even with PW_RENDERFULLCONTENT	Retry with screenshot_background(fullContent=false); if still black, use foreground screenshot
UIA call overhead	~2 ms (focus) / ~100 ms (tree) via Rust native engine; ~300 ms via PowerShell fallback	Rust engine loads automatically; workspace_snapshot uses a 2 s timeout internally
Chrome / WinUI3 UIA elements are empty	Chromium exposes only limited UIA	screenshot(detail='text') auto-detects Chromium and falls back to Windows OCR (hints.chromiumGuard=true). For richer DOM access use browser_open + browser_locate
Chromium title-regex misses when sites rewrite document.title	Guard relies on the - Google Chrome suffix being present; some sites push it off the end of a long title	Title is treated as plain Chrome (UIA runs). OCR path is still reachable via ocrFallback='always' or when UIA returns <5 elements (uiaSparse)
browser_* CDP tools need Chrome launched with --remote-debugging-port	If Chrome is already running on the default profile without the flag, browser_open fails. The CDP E2E suite (tests/e2e/browser-cdp.test.ts) will also fail in that state	Close Chrome first, then browser_open({launch:{}}) will relaunch it in debug mode, or start Chrome manually with --remote-debugging-port=9222 --user-data-dir=C:\tmp\cdp
Layer buffer TTL	Buffer auto-clears after 90s of inactivity → next diffMode becomes an I-frame	After long waits, call workspace_snapshot to explicitly reset the buffer
keyboard(action='type') / keyboard(action='press') follow focus	When window_dock(action='dock')(pin=true) keeps another window on top (e.g. Claude CLI), keystrokes may be absorbed by that window	Call focus_window(title=...) first and verify isActive=true via screenshot(detail='meta') before sending keys
keyboard(action='type') em-dash / smart quotes in Chrome/Edge	Non-ASCII punctuation (em-dash —, en-dash –, smart quotes "" '') can be intercepted as keyboard accelerators, shifting focus to the address bar	Always use use_clipboard=true when the text contains such characters
browser_eval(action='js') on React / Vue / Svelte inputs	Setting element.value = ... or dispatching synthetic events does not update the framework's internal state	Use browser_fill(selector, value) — it uses native prototype setter + InputEvent which does update React/Vue/Svelte state

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Token cost reference

Mode	Tokens	Use case
screenshot (768px PNG)	~443 tok	General visual check
screenshot(dotByDot=true) window	~800 tok	Precise clicking (no coordinate math)
screenshot(diffMode=true)	~160 tok	Post-action diff
screenshot(detail="text")	~100–300 tok	UI interaction (no image)
workspace_snapshot	~2000 tok	Full session orientation

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License

MIT