Codex CLI

Codex CLI (OpenAI)

Commands

Key Flags

Sandbox Modes

• read-only - Can only read files
• workspace-write - Can write to workspace
• danger-full-access - Full system access (use with caution)

Features

• Image inputs - Accepts screenshots and design specs
• Image generation (gpt-image-2) - Generate images via natural language or explicit invocation
• Code review - Reviews changes before commit
• Web search - Can search for information
• MCP integration - Third-party tool support

Image Generation (gpt-image-2)

Codex CLI can generate images using OpenAI's gpt-image-2 - the latest cutting-edge image model with superior realism, prompt adherence, and accurate text rendering in images. It can produce full high-fidelity design mockups for web pages and apps with unprecedented accuracy and control.

How to Invoke

Natural Language (Recommended)

Just describe what you want naturally:

codex "Generate a clean app icon for a fitness tracker, flat design, 512x512"
codex "Create a hero banner for a SaaS landing page showing a dashboard with dark mode"
codex -i screenshot.png "Edit this screenshot to make the button green and add a tooltip"

Explicit Skill Invocation

Include $imagegen anywhere in your prompt to force the image-generation tool. This is a Codex keyword, not a shell variable, so shell examples use single quotes to keep it literal.

codex 'Make a pixel-art sprite sheet for a platformer game $imagegen'
codex 'Generate a logo for my coffee shop $imagegen'

Codex will generate the image(s), display them inline in the terminal (or save them locally). You can iterate on them, attach them to future prompts, or use them in your codebase.

Tips

• Image editing / iteration: Attach a reference image (screenshot, wireframe, mockup) to your prompt. Codex handles multimodal input natively.

  codex -i wireframe.png "Turn this wireframe into a polished UI mockup"
  codex -i design.png "Generate code for this design"
  

• Usage & limits: Images count against your regular Codex usage quota and consume it 3-5x faster than text-only turns (depending on size/quality).

• Heavy/batch work: For production pipelines, set OPENAI_API_KEY in your shell and tell Codex to call the OpenAI Images API directly. It will then use gpt-image-2 with full API pricing and options.

• No config needed: Image generation is enabled by default. Older experimental flags like codex features enable image_generation are no longer required.

Config

Config file: ~/.codex/config.toml

Key config values (set in file or override with -c):

• model -- model name (prefer gpt-5.5)
• model_reasoning_effort -- low, medium, high, xhigh
• model_reasoning_summary -- detailed, concise, none
• model_verbosity -- low, medium, high
• profile -- default profile name
• tool_output_token_limit -- max tokens per tool output

Define profiles for different projects/modes with [profiles.<name>] sections. Override at runtime with -p <name> or -c model_reasoning_effort="high".

In interactive_shell

Do NOT pass -s / --sandbox flags. Codex's read-only and workspace-write sandbox modes apply OS-level filesystem restrictions that break basic shell operations inside the PTY -- zsh can't even create temp files for here-documents, so every write attempt fails with "operation not permitted." The interactive shell overlay already provides supervision (user watches in real-time, Ctrl+Q to kill, Ctrl+T to transfer output), making Codex's sandbox redundant.

Prefer gpt-5.5 for Codex CLI work. For users with a default profile configured to gpt-5.5, just run codex "prompt" to use those defaults -- no model or profile flags needed.

For delegated fire-and-forget runs, prefer mode: "dispatch" so the agent is notified automatically when Codex completes.

// Delegated run with completion notification (recommended default)
interactive_shell({
  command: 'codex "Review this codebase for security issues"',
  mode: "dispatch"
})

// Override reasoning effort for a single delegated run
interactive_shell({
  command: 'codex -c model_reasoning_effort="xhigh" "Complex refactor task"',
  mode: "dispatch"
})

// Headless - use bash instead
bash({ command: 'codex exec "summarize the repo"' })