Choosing an agent

When to pick Claude Code, OpenAI Codex, or Gemini CLI for any given prompt. The full decision tree.

Three agents, three sweet spots. This page is the decision tree.

TL;DR

If you’re unsure, use Claude Code — the default. It handles all three cases competently; the others are optimizations.

The decision tree

1. Is the change small? (One file, one function, one line.)

   Yes: OpenAI Codex. Faster, cheaper. No: continue.

2. Is the change primarily about layout, visual design, or schema modeling?

   Yes: Gemini CLI. Stronger spatial intuition. No: continue.

3. Default to Claude Code

   Multi-file refactors, complex logic, integrations, security-sensitive code — Claude Code is the safe pick.

Worked examples

Prompt	Best agent	Why
”Fix the typo on the homepage”	Codex	Tiny
”Add Stripe subscription billing”	Claude Code	Multi-file, security-sensitive
”Redesign the dashboard with a sidebar”	Gemini	Layout-heavy
”Refactor the auth flow to use a state machine”	Claude Code	Logic refactor
”Make the avatar 2px larger”	Codex	Tiny
”Design a schema for a forum (categories, threads, posts, votes)“	Gemini	Schema modeling
”Add real-time presence to the comment editor”	Claude Code	Multi-file, careful state
”Move the brand color from inline Tailwind to design tokens”	Gemini	Multi-file design
”Add validation to the new-task form”	Codex	Single concern
”Add multi-tenancy to this single-tenant app”	Claude Code	Major architectural change

Switching mid-prompt

If you’ve started typing a prompt with one agent selected, switch the dropdown — your typed text stays. Submit with whichever agent fits.

Workspace defaults

Set a workspace-wide default in agent preferences. Most users default to Claude Code and switch per prompt as needed.

Comparison

Agent	Best for	Speed	Credits
Claude Code	Multi-file refactors, complex logic	Standard	Standard
OpenAI Codex	Tight, single-file changes	~1.5–2× faster	Lower
Gemini CLI	Layout, design, schema	Standard	Standard

Related

Claude Code

Deep dive.

Agent preferences

Set defaults.

Fallback behavior

What happens if your agent is unavailable.