Computer Control Agent Skill

Computer Control Skill

Use Claude's Computer Use API to see and control desktop

environments through screenshots and mouse/keyboard actions.

When To Use

• Automating GUI-based workflows that lack CLI alternatives
• Testing web applications through visual interaction
• Filling forms, navigating menus, or interacting with desktop apps
• Building automation pipelines that need visual verification

When NOT To Use

• Tasks achievable through CLI or API (no GUI needed)
• Browser automation better served by Playwright or CDP

> Why this stays opt-in. Per

> [docs/inclusive-defaults.md][inc] (TRUE-exception

> category 4), Computer Use takes screenshots and

> synthesizes keyboard/mouse input: cross-process side

> effects that must always be explicitly invoked, never

> default-on.

[inc]: ../../../../docs/inclusive-defaults.md

Architecture

The computer use system has three layers:

• Display Toolkit (phantom.display) - executes OS-level

actions via xdotool/scrot on the real or virtual display

• Agent Loop (phantom.loop) - manages the conversation

cycle between Claude API and the display toolkit

• CLI (phantom.cli) - command-line interface for running

tasks or checking environment readiness

User Task
    |
    v
Agent Loop  <---->  Claude API (beta)
    |                   |
    v                   v
Display Toolkit    tool_use responses
    |              (click, type, screenshot)
    v
OS Commands (xdotool, scrot)
    |
    v
Display (X11 / Xvfb / WSLg)

Quick Start

Check environment

cd plugins/phantom
uv run python -m phantom.cli --check

Run a task

export ANTHROPIC_API_KEY="sk-ant-..."
uv run python -m phantom.cli "Open Firefox and search for Claude AI"

Use in Python

from phantom.display import DisplayConfig, DisplayToolkit
from phantom.loop import LoopConfig, run_loop

result = run_loop(
    task="Take a screenshot of the desktop",
    api_key="sk-ant-...",
    loop_config=LoopConfig(
        model="claude-sonnet-5",
        max_iterations=10,
    ),
    display_config=DisplayConfig(width=1920, height=1080),
)

print(f"Done in {result.iterations} iterations")
print(result.final_text)

API Versions

| Model | Tool Version | Beta Flag |

|-------|-------------|-----------|

| Opus 4.6, Sonnet 4.6, Opus 4.5 | computer_20251124 | computer-use-2025-11-24 |

| Sonnet 4.5, Haiku 4.5, older | computer_20250124 | computer-use-2025-01-24 |

The resolve_tool_version() function handles this mapping

automatically based on the model name.

Available Actions

All versions:

• screenshot - capture display
• left_click - click at [x, y]
• type - type text string
• key - press key combo (e.g., ctrl+s)
• mouse_move - move cursor

Enhanced (20250124+):

• scroll - scroll with direction and amount
• left_click_drag - drag between coordinates
• right_click, middle_click, double_click, triple_click
• hold_key - hold key for duration
• wait - pause between actions

Latest (20251124):

• zoom - inspect screen region at full resolution

Safety

Computer use carries risks. Follow these guidelines:

• Use a sandbox: Run in Docker or a VM, not your main OS
• Limit access: Do not provide login credentials unless

necessary, and never for banking or sensitive services

• Set iteration caps: Always use max_iterations to

prevent runaway API costs

• Human approval: For actions with real-world consequences,

add confirmation callbacks via on_action

• Close sensitive apps: Claude sees the full screen via

screenshots; close anything private before starting

Environment Requirements

Linux (native or WSL2 with WSLg):

sudo apt install xdotool scrot xclip

Headless (Docker/CI):

# Install Xvfb for virtual display
sudo apt install xvfb xdotool scrot xclip
Xvfb :1 -screen 0 1920x1080x24 &
export DISPLAY=:1

Prompting Tips

• Be specific about each step of the task
• Add "After each step, take a screenshot and verify" to

catch mistakes early

• Use keyboard shortcuts when UI elements are hard to click
• Provide example screenshots for repeatable workflows
• Set a system prompt with domain-specific instructions

Exit Criteria

• [ ] uv run python -m phantom.cli --check exits 0 before any

task is launched; if it fails, required OS tools (xdotool,

scrot, xclip) are installed or Xvfb is started before

proceeding

• [ ] max_iterations set on every run_loop() call; no task

launched without an explicit iteration cap to prevent runaway

API costs

• [ ] Final result includes result.iterations count and

result.final_text confirming the task outcome; empty

final_text treated as failure, not success

• [ ] Sensitive applications (password managers, banking, private

files) closed before task starts; task prompt does not contain

raw credentials