glass
Give your coding agent hands for the app it's building — launch it, drive it, and verify the
result, without burning a screenshot on every step.
A Rust MCP server that gives an AI coding agent a closed build →
see → interact → debug loop over external native GUI applications.
glass lets an agent launch a GUI app, capture what is on screen, inject mouse and keyboard input, read
the app's logs, and detect visual changes — so a coding agent can build and debug UI applications
independently instead of asking the user "does this look right?".
glass drives apps as an external black box, so it works with any native GUI app regardless of toolkit
or language. It has two Linux backends (X11 and Wayland), a Windows backend, an
Android backend (an AVD emulator, driven over adb from any host), an iOS backend (native
apps in the Simulator over xcrun simctl, with input and the accessibility tree via idb_companion,
including a two-finger pinch), and a macOS backend, behind a platform-agnostic core.
The same input tools work across backends. Default Linux displays and mobile emulators keep input
separate from your desktop; native Windows and macOS currently share it. glass_capabilities with
scope: "session" reports click, scroll and text support and whether each can affect your desktop.
See it
An agent building a GUI app runs it under glass, reproduces a bug from the accessibility tree
(no screenshots), fixes the code, and re-verifies — the loop it otherwise can't close on its own.
Try it yourself.
Try it in 60 seconds
-
Download glass for your platform from the Releases page
and connect it to your agent — glass works with any MCP host
(see which are verified).
-
Get the example app — clone this repo, or download
examples/tasks-demo/tasks_demo.py (on Linux it needs
sudo apt install python3-gi gir1.2-gtk-4.0).
-
Paste this to your agent:
Use glass to run examples/tasks-demo/tasks_demo.py with accessibility on. There's a bug: clicking
Add doesn't add the typed task. Reproduce it by driving the UI and checking the
accessibility tree (don't just screenshot), then find and fix the bug in the code and verify a
task actually appears.
Your agent launches the app, reproduces the bug from the accessibility tree, fixes the one-line
wiring bug, and confirms the task appears — the whole build → see → interact → debug loop, start to
finish. (glass-mcp doctor checks your environment if anything's off.)
The loop in practice
An agent can fill in a form, click Save, and check that the app reports success. When the app exposes
an accessibility tree, the agent works with named controls and verifies changes from text:
glass_start { "run": ["python3", "app.py"] }
glass_do { "actions": [
{ "action": "set_value",
"target": { "query": "account", "role": "TextField", "states": ["enabled"] },
"text": "hello" },
{ "action": "click_element",
"target": { "query": "Save", "role": "Button", "states": ["enabled"] },
"mode": "auto" },
{ "action": "wait_for_element", "name": "Saved" }
] }
glass_logs
Use glass_find_elements to inspect candidates when the intended target is not unique or known well
enough to act on directly. Use glass_a11y_snapshot to explore the app's controls. See the
tool reference for click modes and platform behavior.
For a canvas or custom-rendered app with no accessibility tree, drive it by pixels instead —
glass_screenshot, glass_click {x,y}, and glass_diff, which returns changed_pct + a bbox as
text, so routine checks between screenshots cost no vision tokens. Why the loop is shaped this way:
the build → see → interact → debug loop.
To review a run after the app stops, opt into session evidence recording
with --trace-dir. Glass retains tool inputs and requested results in bounded storage, then
glass-mcp trace inspect and trace export validate the trace and package its evidence in a ZIP.
Recording is off by default; retained app content can contain sensitive data.
Install at a glance
Download the latest build for your platform from the
Releases page, then set up your host:
Every asset is listed in docs/reference/platforms.md.
Prefer to compile, or on an architecture with no published asset? See
docs/how-to/build-from-source.md — it is a single cargo build.
Then connect glass to your agent and run glass-mcp doctor to check
the environment. New here? Follow the tutorial for a guaranteed first
success.
The full toolbox remains the default. For fewer agent tool definitions, start with
glass-mcp --tool-profile lean and use glass_do for actions. Inspect either inventory without
starting a session using glass-mcp tools --json; see tool profiles.
Drive it well — the glass-drive skill
glass needs no app integration and no skill to run, but an agent drives it far more reliably with the
open glass-drive Agent Skill — it stops the agent spending its first
turns rediscovering the verify-cheaply-then-look loop. Installing it is the single highest-leverage
thing you can add when pointing an agent at glass.
Platform support
✓ supported · ◑ partial · – not supported · 🚧 planned.
| Capability | Linux (X11 + Wayland) | Windows | Android (AVD) | iOS (Simulator) | macOS |
|---|
| Capture · input · windows · clipboard · logs | ✓ | ✓ | ✓ | ✓ | ✓ |
| Accessibility (semantic addressing) | ✓ AT-SPI | ✓ UI Automation | ✓ UIAutomator | ✓ idb | ✓ AX |
| Containment / sandboxing | ✓ bubblewrap | ✓ Sandboxie | ✓ the emulator VM | ✓ the Simulator | ✓ Seatbelt |
| Input without desktop interference | ✓ private display | – shared desktop | ✓ emulator | ✓ Simulator | – shared desktop |
| Display isolation (app off your desktop) | ✓ headless Xvfb / sway | – VM needed | ✓ headless emulator | ✓ headless simctl boot | – shared desktop |
Full matrix, per-capability detail, and system requirements:
docs/reference/platforms.md. Transport is MCP over stdio (default) or
network HTTP.
Documentation
The full docs — tutorial, how-to guides, reference, and explanations — are under
docs/. See CHANGELOG.md for release notes, and
Stability and versioning for what a 1.0 release guarantees.
Contributing? CONTRIBUTING.md has the gates a PR has to pass, and
Verify a change covers platform code your own host cannot run.
License
glass is open core, licensed Apache-2.0 — see LICENSE-APACHE.
