OpenAI Codex

OpenAI’s coding model. The fastest agent in vly for small, surgical changes — one-line fixes, single-function rewrites, tight refactors.

OpenAI Codex is the speed pick. When the change is small and well-defined — a typo, a one-line bug fix, a single function rewrite — Codex completes it noticeably faster than Claude Code or Gemini CLI.

Strengths

Surgical edits

Small, targeted changes to a single file or function. Codex’s outputs are tight, with minimal collateral.

Speed

Typically 1.5–2× faster than Claude Code on small changes. Compounds over many small iterations.

Low credit cost

Smaller, cheaper model — small changes cost fewer credits.

Style consistency

Matches the surrounding code’s style without drifting.

When to pick Codex

One-line fixes

“Fix the typo on the homepage hero.” Codex.

Single-function rewrites

“Refactor formatDate to use Intl.DateTimeFormat instead of manual concatenation.” Codex.

Style tweaks

“Make the avatar 2px larger and add a subtle shadow.” Codex.

Tight bug fixes

“When the user clicks delete, the confirmation modal shows up but doesn’t close on confirm. Fix it.” Codex.

When not to pick Codex

For multi-file features, large refactors, or anything that requires reasoning about the whole project, Claude Code is better. For multi-file design or schema work, Gemini CLI often shines.

Usage

Codex is available as a per-prompt agent override:

1. Submit your prompt as usual.
2. Below the input, change the agent dropdown to OpenAI Codex.
3. Submit.

Or set it as the workspace default in agent preferences.

Tips

Codex shines on hot iteration loops. Quick visual tweaks, repeated style adjustments, fast bug fixes — keep Codex selected and fly through 20 small prompts in 10 minutes.

For very small changes, consider Code mode. Sometimes editing the file directly is faster than even the fastest agent.

Related

Claude Code

The default. For larger changes.

Gemini CLI

For multi-file design work.

Choosing an agent

The full decision tree.