cmux-cua — macOS Computer Use Skill for Claude Code and Codex
Drives real macOS apps from a cmux agent session: accessibility tree, screenshots, clicks, typing and scrolling. Runs only after the user explicitly asks for it.
npx skills add manaflow-ai/cmux --skill cmux-cua -a claude-codeWhat cmux-cua does
The skill attaches a local computer-use engine to every agent session that cmux launches. The agent gets MCP tools under the cmux-cua namespace: reading the accessibility tree, taking screenshots, clicking, typing, scrolling and dragging. The engine ships inside a separate helper called **cmux Computer Use**, so macOS permissions are granted to that helper rather than to cmux itself. Screen Recording can be turned on without restarting cmux.
A direct request like $cmux-cua acts as the opt-in. If the Computer Use toggle is off, cmux turns the runtime on and opens onboarding. The first functional tool call from a current session also opens setup when permissions are missing. Setup never grants anything by itself — the user still completes each macOS permission step manually.
In Codex sessions launched by cmux, the native computer_use provider is disabled. Use only the namespaced cmux-cua tools, never Codex's built-in computer tool or a direct helper launch. The hard kill switch is CMUX_COMPUTER_USE_MCP_DISABLED=1. The skill attaches only to live cmux-launched sessions; hook-disabled and stale-socket sessions do not get it.
What it helps with
- read the accessibility tree of a macOS app
- click, type or scroll in a real application window
- capture a screenshot for the agent to analyze
- grant Accessibility and Screen Recording to the helper, not to cmux itself
- disable native Codex computer use inside cmux sessions
Example prompts for the agent
- Open Safari via $cmux-cua and read the page accessibility tree.
- Take a screenshot of the current window and tell me what it shows.
- Click the Save button in the app preferences.
How to install cmux-cua
1Skills CLI (Vercel)
npx skills add manaflow-ai/cmux --skill cmux-cua -a claude-code2Manually: put the files in place
~/.claude/skills/cmux-cua/SKILL.mdCopy the whole skill folder; for one project use .claude/skills/cmux-cua/
1Skills CLI (Vercel)
npx skills add manaflow-ai/cmux --skill cmux-cua -a codex2Manually: put the files in place
.agents/skills/cmux-cua/SKILL.mdFor all projects use ~/.agents/skills/
1Skills CLI (Vercel)
npx skills add manaflow-ai/cmux --skill cmux-cua -a cursor2Manually: put the files in place
.cursor/skills/cmux-cua/SKILL.mdCursor also reads .agents/skills/ and .claude/skills/
1GitHub CLI
gh skill install manaflow-ai/cmux cmux-cua2Manually: put the files in place
.github/skills/cmux-cua/SKILL.md1Skills CLI (Vercel)
npx skills add manaflow-ai/cmux --skill cmux-cua -a gemini-cli2Platform CLI
gemini skills install https://github.com/manaflow-ai/cmux --path skills/cmux-cuaManually: put the files in place
.devin/skills/cmux-cua/SKILL.mdThe legacy .windsurf/skills/ path still works
Skills CLI (Vercel)
npx skills add manaflow-ai/cmux --skill cmux-cua -a opencodeClaude.ai
Zip the folder and upload it in Settings → Capabilities → Skills
Step by step, with commands for each platform: How to install skills in Claude Code: five ways
Questions about cmux-cua
How do I install cmux-cua in Claude Code?
Run npx skills add manaflow-ai/cmux --skill cmux-cua -a claude-code, then open ~/.claude/skills/cmux-cua/SKILL.md.
How do I install cmux-cua in Codex?
Run npx skills add manaflow-ai/cmux --skill cmux-cua -a codex, then open .agents/skills/cmux-cua/SKILL.md.
What permissions does the skill need?
Two macOS permissions are required: Accessibility and Screen Recording. They are granted to the cmux Computer Use helper, so enabling Screen Recording does not require a cmux restart.
