The 15-minute setup to get OpenAI's Codex agent running on your Mac, paired with your phone, and shipping real work for you.
OpenAI just put Codex on your phone. That means you can now have an AI agent running on your Mac for hours while you're walking around with your iPhone, checking in on its progress and approving its work. It's the closest thing yet to "real assistant that does actual work."
But most people get stuck before they even start. The install is confusing. The plan tier requirements are unclear. The first prompts feel like dev-tool territory if you don't write code. This guide fixes that.
By the end you'll have Codex installed, your first project running, your phone paired with your Mac, and three real prompts you can use today. Even if you've never opened a terminal in your life.
A paid ChatGPT plan. Codex is included with every paid ChatGPT subscription, no separate sign-up needed. The recommended starting tier is Plus at $20/month. It gives you full Codex access on Web, CLI, IDE, and iOS, with enough capacity (15 to 80 GPT-5.5 messages per 5-hour window) to run a few multi-step tasks per session. Free and Go ($8) work for trying it out, but you'll hit limits fast on real work.
A Mac or Windows computer. The Codex desktop app runs on macOS (Apple Silicon or Intel) and Windows (via the Microsoft Store). Linux support is coming. If you're on Windows, the Codex CLI works fine too.
A folder for your project. Codex operates inside a folder you pick. Make a new one on your Desktop called "Codex" before you start. That's where your work will live.
About 15 minutes for the full setup including pairing your phone.
Step 1
Go to chatgpt.com and make sure you're on a paid plan (Plus is the sweet spot). Then go to developers.openai.com/codex/quickstart and download the Codex desktop app for your operating system. Install it and launch it.
Critical install gotcha
If you're using the CLI instead of the desktop app, the correct npm package is @openai/codex, not "codex." Running npm i -g codex installs an unrelated 2012 project and silently does nothing. The right command is npm i -g @openai/codex.
Step 2
When Codex opens, it asks you to sign in with your ChatGPT account. Click sign in, complete the OAuth flow in your browser, and come back to the app. Then it asks you to pick a project folder. Select the Codex folder you made on your Desktop earlier. That's now Codex's workspace. It will only edit files inside that folder by default.
Step 3
Type into the chat box. OpenAI's literal suggested first prompt is "Tell me about this project." If your folder is empty, ask it something practical instead. Drop a CSV, a resume, or any document into your project folder, then ask Codex to do something useful with it.
Three prompts to try first
Pro tip
Start every new thread with a "read first" prompt before you ask Codex to edit anything. Example: "Read everything in this folder and tell me what's here." That gives Codex context to make better decisions on the actual task. OpenAI's own best-practice principle is "read first, do not edit yet."
Step 4
This is the part that changes how you use Codex. On the desktop app, open the mobile pairing screen (it shows a QR code). On your iPhone or Android, open the latest ChatGPT app, tap into Codex, and scan the QR code. Done. Under a minute.
Now you can start tasks from your phone, get push notifications when Codex finishes or needs your approval, review the diffs and terminal output, and approve commands. All while your Mac quietly does the work at home.
What this unlocks
Kick off a long-running task before you leave the house. Walk to coffee. Get a push when Codex is ready for input. Approve from your phone. Keep walking. The agent works in the background while you live your life. This was impossible 6 months ago.
Step 5
Codex has 3 approval modes. Pick the one that matches how cautious you want to be:
Read-only: Codex can read your files and answer questions. It asks before editing anything, running commands, or accessing the network. Safest for beginners trying it out.
Auto (default): Codex can read and edit files inside your workspace and run local commands. It asks before editing outside the workspace or accessing the network. This is the right setting for daily use.
Full Access (YOLO mode): No sandboxing, no approval prompts. OpenAI flags this as "elevated risk and not recommended." Stay out of this unless you really know what you're doing.
Common beginner mistake
Don't switch to YOLO mode just because the approval prompts are annoying. The prompts are actually teaching you what's risky. Stay in Auto mode for at least your first month. You'll develop a feel for what Codex is about to do, and you'll catch the things you don't want before they happen.
1. Prompts that are way too broad. "Refactor the whole project" or "build me a complete website" sets Codex up to fail. Start each thread with a read/explore prompt, then add one specific task at a time.
2. One thread for everything. Context drifts when you stuff multiple tasks into one chat. Use a new thread per task. Codex is built for parallel threads.
3. Treating it like a chatbot you babysit. Codex is designed to run in the background and ping you when it needs you. Sitting and watching defeats the whole point. Start a task, switch to something else, let it ping you.
4. The wrong npm install. Already covered above. npm i -g @openai/codex. Not just "codex."
5. Skipping the approval prompts. Beginners flip to YOLO mode the first time the approvals get annoying. Stay in Auto. The approvals are showing you what a real agent is actually doing.
Where to learn more
OpenAI's official docs are at developers.openai.com/codex. The quickstart, pricing, sandboxing, and use-cases pages are the highest-signal reading. Skip the third-party tutorials until you've spent a week with Codex yourself.
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