name: codex-cli
description: Use OpenAI's Codex CLI to invoke GPT models from the command line. Use when you need a second AI opinion, want to verify your work, or need OpenAI-specific capabilities.
argument-hint: [prompt]
allowed-tools: Bash, Read

Codex CLI

Use the codex command to invoke OpenAI's Codex AI from the command line.

Prerequisites

The user must have already:
1. Installed Codex CLI: npm install -g @openai/codex
2. Logged in: run codex login

Basic Command

Use exec for non-interactive mode with the latest model:

codex exec -m gpt-5.2-codex "Your prompt here"

Models

File References

Use @ in prompts to include files:

codex exec -m gpt-5.2-codex "Review @src/main.js"

Piped Input

cat file.txt | codex exec -m gpt-5.2-codex "Summarize this"
git diff | codex exec -m gpt-5.2-codex "Write a commit message"
echo "your prompt" | codex exec -m gpt-5.2-codex -

JSON Output

For programmatic parsing:

codex exec -m gpt-5.2-codex --json "Query" | jq

File Output

Write result to file:

codex exec -m gpt-5.2-codex -o output.md "Generate docs"

Key Flags

Sandbox Modes

# Safe analysis only
codex exec --sandbox read-only -m gpt-5.2-codex "review code"

# Allow file edits
codex exec --sandbox workspace-write -m gpt-5.2-codex "fix linting errors"

Session Resume

Continue a previous conversation:

codex exec resume --last "follow up question"

Exit Codes

Standard exit codes - 0 for success, non-zero for errors.

When Using This Skill

If $ARGUMENTS is provided, construct and run the appropriate codex command for that prompt.

Otherwise, use Codex CLI when you need to:
- Get a second opinion on code or analysis
- Verify your own output
- Leverage OpenAI's specific strengths