Axterminator
MCP server for macOS desktop automation. Background GUI testing, 30 tools, audio capture, camera, virtual desktops. Built in Rust.
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AXTerminator
MCP server that gives AI agents the ability to see and control macOS applications.
Deploy Β· MCP Tools Β· CLI Β· Query Syntax Β· AX-first vs Vision-first Β· FAQ Β· Troubleshooting Β· Wiki Β· Known Limitations
Up to 34+ MCP tools (27 core + optional audio, camera, spaces). Background interaction via the macOS Accessibility API. 379us per element access. Audio capture, camera input, virtual desktop isolation. Your AI agent connects and your Mac becomes an extension of it.
Platform scope. AX-first-with-vision-fallback is macOS-only. iOS/iPadOS support is tracked in #43 as a future capability and, when shipped, will be screenshot + vision only β the idevice/RPPairing surface does not expose AX trees for third-party apps, and UIAutomation would require an on-device test runner (breaks the "mac-only agent, no on-device prereqs" contract). Reported screenshot latency via CoreDeviceProxy: ~350ms USB, ~700ms WiFi (credit @m13v). tvOS is unverified β the RSD surface is narrower than idevice's tvOS target suggests; please open an issue with device evidence if you've tested. See #42 for the AX-first-vs-vision-first positioning rationale.
Deploy
Tell your AI assistant (recommended):
Read https://github.com/MikkoParkkola/axterminator and install axterminator as my macOS GUI automation MCP server
Your agent will install the binary, wire itself up, and request accessibility permissions. Works in Claude Code, Cursor, Windsurf, and any AI with terminal access.
Or install manually:
brew install MikkoParkkola/tap/axterminator
Grant accessibility permissions: System Settings > Privacy & Security > Accessibility (add your terminal app).
axterminator mcp install auto-detects your AI client. Specify one with --client:
axterminator mcp install # Claude Desktop (default)
axterminator mcp install --client claude-code # Claude Code
axterminator mcp install --client cursor # Cursor
axterminator mcp install --client windsurf # Windsurf
axterminator mcp install --client codex # OpenAI Codex CLI
axterminator mcp install --client vscode # VS Code Copilot
axterminator mcp install --client zed # Zed
axterminator mcp install --dry-run # Preview without writing
Also supported: gemini, amazon-q, lm-studio.
More install options
# From crates.io
cargo install axterminator --features cli
# Build from source
git clone https://github.com/MikkoParkkola/axterminator
cd axterminator
cargo build --release --features cli
# Manual JSON (Claude Desktop, Cursor, Windsurf, etc.)
# { "mcpServers": { "axterminator": { "command": "axterminator", "args": ["mcp", "serve"] } } }
Codex config
For Codex (~/.codex/config.toml):
[mcp_servers.axterminator]
command = "axterminator"
args = ["mcp", "serve"]
Done. Your agent has 27 core tools (up to 34+ with all feature flags) to control any macOS app.
MCP Tools
| Category | Tools | What the agent can do |
|---|---|---|
| GUI | ax_connect, ax_find, ax_click, ax_click_at, ax_type, ax_set_value, ax_get_value, ax_scroll, ax_drag, ax_key_press | Connect to apps, find elements, interact |
| Observe | ax_is_accessible, ax_screenshot, ax_get_tree, ax_get_attributes, ax_list_windows, ax_list_apps, ax_wait_idle | Check permissions, see UI state, screenshots |
| Verify | ax_assert, ax_find_visual, ax_visual_diff, ax_a11y_audit | Assert element state, AI vision fallback, visual regression, WCAG audit |
| System | ax_clipboard, ax_run_script, ax_undo, ax_session_info, ax_analyze | Clipboard, AppleScript/JXA, undo actions, session state, UI analysis |
| Audio | ax_listen, ax_speak, ax_audio_voices, ax_audio_devices | Capture mic/system audio, text-to-speech, inspect installed macOS voices |
| Camera | ax_camera_capture, ax_gesture_detect, ax_gesture_listen | Camera frames, gesture recognition |
| Spaces | ax_list_spaces, ax_create_space, ax_move_to_space, ax_switch_space, ax_destroy_space | Virtual desktop isolation |
Resources
Agents can browse app state without tool calls:
| Resource | What |
|---|---|
axterminator://apps | Running applications |
axterminator://app/{name}/tree | Live element hierarchy |
axterminator://app/{name}/screenshot | Current screenshot |
axterminator://app/{name}/state | Focused element, window title |
axterminator://system/displays | Monitor layout |
Security
Destructive actions require confirmation via elicitation. HTTP transport requires bearer token auth. The AI has hands, not root.
CLI
axterminator apps # List accessible apps
axterminator find "Save" --app Safari # Find element
axterminator click "Save" --app Safari # Click it
axterminator screenshot --app Safari # Capture screenshot
axterminator tree --app Finder # Element hierarchy
axterminator mcp serve --http 8080 --token secret # HTTP transport
Query Syntax
# Simple text β matches ANY of: title, description, value, label, identifier
axterminator find "Save" --app Safari
# By role
axterminator find "role:AXButton" --app Safari
# Combined role + attribute (AND)
axterminator find "role:AXButton title:Save" --app Safari
# By description (useful for apps like Calculator)
axterminator find "description:equals" --app Calculator
# By value
axterminator find "value:42" --app Calculator
# XPath-like
axterminator find "//AXButton[@AXTitle='Save']" --app Safari
How It Works
AXTerminator uses an undocumented behavior of Apple's Accessibility API: AXUIElementPerformAction() works on unfocused windows. Your agent clicks buttons in one app while you work in another. Neither notices.
379us per element access (Criterion, M1 MacBook Pro). Appium needs 500ms for the same thing.
7-strategy self-healing locators survive UI changes: data_testid, aria_label, identifier, title, xpath, position, visual_vlm.
AX-first vs Vision-first
OpenAI Codex computer use, Anthropic Claude Computer Use, Google Gemini Operator, and Perplexity Personal Computer all use the same paradigm: screenshot β vision LLM β pixel coordinates β cursor click. The vendor changes; the paradigm does not.
axterminator uses the opposite default: AX semantic tree β element reference β action. Vision is a fallback for the rare surfaces the AX tree cannot reach (canvas apps, games, OpenGL/Metal renderers).
| Dimension | Vision-first (Codex CU / Claude CU / Gemini / β¦) | AX-first (axterminator) |
|---|---|---|
| Speed | seconds per action (vision round-trip + LLM) | ~379 Β΅s per action (measured, Criterion) |
| Cost | vision tokens on every action | ~free (AX API call) |
| Reliability | pixel-brittle β breaks on theme, font, layout changes | element-stable β semantic addressing survives UI changes |
| Background | visible cursor movement | truly background β no visible cursor |
| Dense / labeled UIs | struggles with small targets | reads labels directly from the AX tree |
| Canvas / games / OpenGL | works (universal fallback) | needs vision fallback (ax_find_visual) |
| Cross-platform | anywhere a screenshot works | macOS only (see #43 for iOS roadmap) |
The key insight: axterminator is not a competitor to those agents β it is a layer underneath them. Any agent that can call an MCP tool (Claude Code, Codex CLI, Cursor, Windsurf, VS Code Copilot, Gemini CLI) can use axterminator as its hands. They provide reasoning; axterminator provides reliable, cheap, background-safe action.
Coverage gate. Before investing heavily in vision-fallback features, run the AX coverage audit below for one week on your actual app surface. If >95% of your actions resolve via AX, vision fallback is a nice-to-have. If <80%, expand the vision fallback path first. See benches/probes/README.md for the audit harness.
FAQ
Why use this instead of Codex computer use / Claude Computer Use / Gemini Operator?
You probably use both. Those agents call axterminator as an MCP tool. axterminator gives them AX-semantic actions that are ~1,000Γ faster and cost nothing per call. The vision model stays for tasks that genuinely need it (canvas apps, games), not for clicking a Save button in TextEdit.
Isn't vision-first simpler β no setup, works everywhere?
It works everywhere vision works: foreground, focused, slow, expensive. axterminator works in the background, costs nothing, and is sub-millisecond. For automation of native macOS apps β the majority of business software β AX is strictly better. Vision is the escape hatch, not the default.
What app surfaces does axterminator cover?
Any macOS app that exposes the Accessibility API: all native AppKit/SwiftUI apps, Electron apps, web apps in Chrome/Safari/Firefox, terminal apps. Canvas-only surfaces (Figma canvas, game renderers, video players) use ax_find_visual β the built-in vision fallback that tries AX first and falls back to VLM automatically.
Does it work with agents that are already doing computer use?
Yes. Add axterminator mcp install --client codex (or --client claude-code, etc.) and the agent gains 34 semantic tools it can call instead of pixel-clicking. It doesn't replace the agent's vision; it gives the agent a faster, cheaper path for the 90%+ of actions that don't need vision.
Who is it for beyond developers?
- Executive assistants: file triage, calendar entry, copy-paste between apps β all in the background while you work
- Sales ops: CRM entry, proposal generation across native apps, screen scraping structured data from dense UIs
- Event coordinators: spreadsheet-to-calendar sync, venue research across multiple apps, confirmation email drafts β reliable because it reads labels semantically, not by pixel position
Known Limitations
| Operation | Background? | Notes |
|---|---|---|
| Click, press, read values, screenshots | Yes | Core operations work without focus |
| Text input | Partial | Some apps need focused text field |
| Drag, system dialogs | No | Require cursor control / always grab focus |
| Gesture recognition | Yes | Verified: thumbs_up at 88.8% confidence |
| Speech transcription | Yes | Verified: on-device, requires Dictation enabled |
Platform coverage (see #43):
| Platform | AX tree | Screenshot | App launch | Status |
|---|---|---|---|---|
| macOS 12+ | β | β | β | Shipped; sub-ms AX path |
| iOS / iPadOS | β (third-party apps) | β (~350ms USB / ~700ms WiFi) | β | Planned, screenshot + vision only β no AX semantics |
| tvOS | β | β | β | Unverified β RSD surface narrower than idevice suggests |
| visionOS / watchOS | β | β | β | Out of scope |
Troubleshooting
| Symptom | Cause | Fix |
|---|---|---|
Accessibility: DISABLED | No permission granted | System Settings > Privacy & Security > Accessibility |
Element not found for short labels | App uses AXDescription not AXTitle | Try description:label or inspect with axterminator tree |
Application not found | Wrong name or app not running | Use bundle ID: --bundle-id com.apple.calculator |
AI agents: Fetch llms.txt for machine-readable installation instructions.
Feature Flags
The Homebrew formula includes all features. When building from source, select capabilities with feature flags:
cargo build --release --features "cli,audio,camera,spaces"
| Flag | What |
|---|---|
cli | CLI + MCP server (default) |
audio | Microphone/system audio, speech |
camera | Camera capture, gesture detection |
spaces | Virtual desktop management |
http-transport | HTTP MCP transport with auth |
Community
- Wiki -- Full documentation
- Discussions -- Questions, ideas, show-and-tell
- Issues -- Bugs
Acknowledgements
Inspired by Terminator by mediar-ai, which pioneered accessible desktop GUI automation on Windows.
For AI Agents
Machine-readable installation guide: llms.txt
Your agent can fetch this URL to get step-by-step installation, MCP config for every host, and troubleshooting.
Ecosystem
axterminator is part of a suite of MCP tools:
| Tool | Description |
|---|---|
| mcp-gateway | Universal MCP gateway β compact 12-15 tool surface replaces 100+ registrations |
| trvl | AI travel agent β 36 MCP tools for flights, hotels, ground transport |
| nab | Web content extraction β fetch any URL with cookies + anti-bot bypass |
| axterminator | macOS GUI automation β 34 MCP tools via Accessibility API |
License
AXTerminator is free for personal, research, educational, noncommercial open-source, and free public-good projects with attribution.
Business use requires a written commercial license. See LICENSE.md and COMMERCIAL.md.
Earlier releases published under MIT OR Apache-2.0 remain under those earlier
license grants for those earlier versions only.
