You commented BETTER, so you want the setup that gets ChatGPT and Gemini working inside Claude Code with you — not three tabs you keep flipping between. Here's the whole thing: what each model does, how to wire them in, and how to tell Claude when to hand off. You already opted in, so let's go.
Claude Code stays your builder. It writes the code, runs the terminal, makes the changes.
GPT becomes your reviewer — a second set of eyes on whatever Claude just wrote.
And Gemini's the one that reads the giant stuff: long videos, 300-page PDFs, files too big for Claude to hold. (It's got a million-token window, so it doesn't choke on the things Claude has to cut off halfway.)
Here's the real reason running three models beats one — it's not "more power." It's different blind spots. The model that wrote the code is the worst one to catch its own mistakes (same reason you can't proofread your own writing — your brain reads what it meant to type). A different model sees what Claude can't.
Rule of thumb: the model that wrote the code is the worst one to review it.
You're connecting the other two to Claude Code as MCP tools. That's what lets Claude call them mid-task instead of you copy-pasting between apps.
Install the Gemini CLI and log in with your Google account (the free tier covers a lot before it slows you down). Then install Codex, OpenAI's CLI, and sign in with the ChatGPT subscription you already pay for — no new bill.
Then add each one to Claude Code as an MCP server, so Claude gets a tool it can fire off — like handing a 200-page PDF to Gemini without leaving the terminal.
The real reason "free" matters here: most multi-model setups charge you per API call, and that meter runs fast when you're iterating. Routing through CLIs tied to plans you already have means no new subscription and no surprise token bill at the end of the month.
(Honest heads-up: those free tiers rate-limit. Gemini's fast model especially — on a heavy day you'll hit a wall and have to wait a bit. Real, but not a dealbreaker.)
You're not buying anything new. You're plugging in what you already pay for.
Wiring it up isn't enough. Claude won't ask the other two for help unless you tell it when to.
Easiest move: add a few lines to your CLAUDE.md. Something like — "After writing any new feature, send the diff to GPT for review before calling it done. Any file over 1,000 lines, or any PDF or video, send to Gemini to read and summarize first." Now it happens on its own.
Or make a slash command (like /review) that runs the whole hand-off in one shot.
You're probably picturing some complicated agent framework with a diagram. It's really two CLIs and a paragraph of instructions telling Claude who to ask for what.
The wiring is the easy part. The instructions are what turn three tools into a team.