Codex earns its place because it works beside Claude Code, not because it replaces it. One model shouldn’t be the whole team.
Picture a second reviewer at the same desk. The first has worked the file, made decisions, and built momentum. The second comes in fresh, sees the same folder, and catches what the first missed. It inspects the same files, diff, and tests, so the review is concrete, not theoretical. Different models have different tendencies, so having Codex review Claude beats asking one model to grade its own homework.
How it shows up
In a codebase, Codex can inspect files, make edits, run commands, or review a change before it becomes a pull request. It’s the stricter reviewer in a cross-model review loop: Claude builds, Codex reviews, Claude fixes, Codex checks again. It isn’t invested in the first draft, so it may be harsher, and that’s useful. The same pattern applies to documents, vault entries, and instructions: if the work lives in files, Codex can help check it.
Why you care
When AI makes the first draft cheap, review matters more, not less. The real risk is that plausible work piles up fast and nobody checks it. A second model gives you another set of eyes before the work reaches a client, a repo, or production.