Codex CLI
Codex CLI is OpenAI's terminal coding agent — open-source, Rust-based, runs locally on macOS, Linux, and Windows. It reads your repo, edits files, runs commands, and calls OpenAI's reasoning models (gpt-5.5 by default; gpt-5.4 fallback when 5.5 isn't available) with tool use. It's the closest analogue to Claude Code from the OpenAI side. Install via Homebrew, npm, or a direct binary download. MCP integration shipped in 2025. Every page below is sourced from github.com/openai/codex and developers.openai.com/codex/cli. Sush hasn't standalone-installed it yet.
- CDX.1 Codex CLI, plainly sourced
Five-minute orientation to Codex CLI — OpenAI's terminal coding agent. Open-source, Rust-based, runs locally. What it does, where it runs, what it costs, and where it fits vs Claude Code, Aider, and GitHub Copilot CLI.
- CDX.2 Install Codex CLI sourced
Four install paths for Codex CLI — npm (cross-platform), Homebrew cask (macOS), a direct binary download, or build from source. Auth on first run, sanity-check, and where files land.
- CDX.3 Auth + API key — sign-in paths for Codex CLI sourced
Four ways to authenticate Codex CLI — ChatGPT OAuth (browser), device code (headless), API key, and Azure OpenAI / Amazon Bedrock providers. Plus credential storage modes, corporate CA setup, and what differs between ChatGPT-plan and API-key sign-in.
- CDX.4 What Codex CLI is good at sourced
Five use cases the official docs emphasise — write code, understand unfamiliar codebases, review code, debug and fix problems, automate development tasks. Plus the non-interactive `codex exec` patterns for CI/CD and the scenarios where you'd reach for a different tool.
- CDX.5 Pitfalls and rough edges sourced
The rough edges Codex CLI users hit in week one — sandbox failures inside Docker, WSL1 not supported, deprecated flags, untrusted project gotchas, fast-mode-vs-API-key, runaway costs, and corporate-network setup.
- CDX.6 MCP integration — wiring tools into Codex sourced
How Codex CLI uses Model Context Protocol — adding MCP servers (Context7, Figma, Playwright, your own), supported transports (STDIO + Streamable HTTP), built-in MCPs (OpenAI Docs, Memories), and running Codex itself as an MCP server.
- CDX.7 Models — picking the right one for the task sourced
The current OpenAI models available to Codex CLI — GPT-5.5 (recommended), GPT-5.4, GPT-5.4-mini, GPT-5.3-Codex (cloud), GPT-5.3-Codex-Spark (preview). How to switch mid-session, how to set reasoning effort, and what fast mode actually does.
- CDX.8 Updates feed — what's been shipping sourced
Codex CLI ships roughly weekly. This page summarises the last six months of major releases — what landed, what got deprecated, what's pre-release — plus where to subscribe to the official changelog.