Codex CLI

Codex CLI is OpenAI's official coding CLI for the GPT-5 codex family.

Prerequisites

• Codex CLI installed
• A key in a group containing GPT-5 codex (recommended: codex)

Config directory

OS	Path
macOS / Linux	~/.codex/
Windows	%userprofile%\.codex\

Create the directory manually if it doesn't exist. Two files needed: config.toml and auth.json.

config.toml

model = "gpt-5.1-codex"
model_provider = "pulseneko"

[model_providers.pulseneko]
name = "PulseNeko Bridge"
base_url = "https://bridge.pulseneko.com/v1"
wire_api = "responses"
requires_openai_auth = true

Fields:

• model — default model (switchable in-session)
• wire_api = "responses" — Codex CLI uses /v1/responses, not chat completions
• requires_openai_auth = true — sends Authorization: Bearer sk-…

auth.json

{
  "OPENAI_API_KEY": "sk-your-key"
}

AGENTS.md (optional)

~/.codex/AGENTS.md is injected as a global system prompt:

• Preferred language
• Code style conventions
• Things never to do (e.g. git push --force)

Recommended models

Model	Best for
gpt-5.1-codex	Daily driver
gpt-5.1-codex-mini	Lighter tasks, cheap
gpt-5.3-codex	Newer reasoning (if available in your group)

Full list on Model Catalog under codex group.

Verify

codex

Error	Cause
provider not found	model_provider doesn't match [model_providers.xxx] section
401	Wrong key in auth.json
wire_api mismatch	Must be responses, not chat

Switching model

In-session: /model gpt-5.1-codex-mini etc.

More

• CLI overview
• Groups