mtell

mtell is a CLI for driving a machine over VNC. It is useful when the task cannot be completed over SSH alone, which is a common case when automating GUI-heavy macOS workflows.

An mtell program can mix plain text typing with structured commands for waiting, pressing keys, clicking text found on screen, and delegating more complex flows to OpenAI's Computer use.

Here is a quick demo using a local Tart VM:

mtell.mp4

Requirements

• A reachable VNC server, for example example.com:5900 or vnc://:password@example.com:5900
• macOS on the machine running mtell for OCR-based commands such as <wait '...'> and <click '...'>
• OPENAI_API_KEY if you want to use <prompt '...'>

Current limitations:

• OCR-backed commands rely on Apple Vision, so they are currently macOS-only

Installation

Using Homebrew

brew install cirruslabs/cli/mtell

Using Go

go install github.com/cirruslabs/mtell@latest

Quickstart

The CLI takes a single PROGRAM argument:

mtell --vnc "vnc://:password@localhost:5900" PROGRAM

A program is just text plus angle-bracket commands:

• Plain text is typed literally
• Commands such as <enter> or <wait10s> are executed in place
• OCR-based commands use single-quoted patterns and support regular expressions

Examples:

# Type credentials and submit
mtell --vnc "vnc://:password@localhost:5900" "admin<tab>s3cret<enter>"

# Wait for a screen to appear, then click a button by visible text
mtell --vnc "vnc://:password@localhost:5900" \
  "<wait30s><click 'Select Your Country or Region'>"

# Use a regular expression to wait for text on screen
mtell --vnc "vnc://:password@localhost:5900" \
  "<wait 'FileVault( Disk)? Encryption'><click 'Continue'>"

# Let OpenAI drive the UI for a more complex task
OPENAI_API_KEY=... mtell --vnc "vnc://:password@localhost:5900" \
  "<prompt 'Accept the dialog and close the currently active window.'>"

Useful flags:

• --input-delay 250ms adjusts the delay between input actions
• --debug enables verbose logs
• --version prints the version

Reference

Typing

Any text outside <...> is typed literally:

• hello world
• user@example.com<tab>hunter2<enter>

Waiting

These commands are useful for loading screens and synchronization:

• <wait10> waits 10 seconds
• <wait5m15s> waits 5 minutes and 15 seconds
• <wait 'Choose Your Country'> waits until text matching the pattern appears on screen

Mouse

These commands use OCR to locate text on screen:

• <click 'Accept'> waits for the pattern to appear, then clicks the center of its bounding box

Keyboard

Use the following commands to press keys:

• <bs>, <del>, <enter>, <return>, <esc>, <tab>, <spacebar> for editing
• <insert>, <home>, <end>, <pageUp>, <pageDown> for navigation
• <up>, <down>, <left>, <right> for arrow keys
• <f1>-<f12> for function keys
• <menu> for the context menu key
• <leftAlt>, <rightAlt> for Alt
• <leftCtrl>, <rightCtrl> for Control
• <leftShift>, <rightShift> for Shift
• <leftSuper>, <rightSuper> for Super
• <leftCommand>, <rightCommand> for Command on macOS
• <leftOption>, <rightOption> for Option on macOS

Any keyboard command can be modified with On or Off:

• <leftShift> presses and releases Shift
• <leftShiftOn> presses Shift without releasing it
• <leftShiftOff> releases Shift

Computer use

These commands are powered by OpenAI's Computer use:

• <prompt 'Open Safari and dismiss any first-run dialogs.'> operates the UI using natural language

Background

This project is heavily inspired by Packer's boot_command, but extends its command set and lets you run those commands anywhere you can start a binary.

Special thanks to Tor Arne Vestbø, who contributed the initial <wait 'text'> implementation to Packer builder for Tart VMs. That work made it clear that boot_command could be pushed further with screen text recognition and higher-level UI automation.