Codex AI Engineering FAQs

Question 1

Which AI models does the Codex skill use?

Accepted Answer

By default, it uses GPT-5.2, but it also supports GPT-5.2-max for ultra-complex reasoning, GPT-5.2-mini for cost-efficient coding, and GPT-5.1-thinking for deep analysis.

Question 2

Can I continue a previous Codex session?

Accepted Answer

Absolutely. By using the 'codex resume' command, the skill pipes your new prompt into the previous session, maintaining the same model and context for iterative work.

Question 3

What is the Codex skill for Claude Code?

Accepted Answer

The Codex skill is a specialized extension that enables Claude Code to interface with the Codex CLI, allowing it to use GPT-5.2 models for advanced software engineering tasks like automated editing and complex problem-solving.

Question 4

How do reasoning effort levels work?

Accepted Answer

Reasoning effort levels (low, medium, high, xhigh) allow you to control how much cognitive resources the AI spends on a task. Use 'low' for simple formatting and 'xhigh' for complex architectural changes.

Question 5

Is the Codex skill safe for my local files?

Accepted Answer

Yes, the skill uses sandbox modes. You can set it to 'read-only' for analysis or 'workspace-write' when you want the AI to apply edits to your local codebase.

Codex AI Engineering

Key Features

Use Cases

Codex AI Engineering

Key Features

Use Cases