---
title: GPT‐5.3‐Codex
link: https://ampcode.com/news/gpt-5.3-codex
source: ampcode-com
published: 2026-02-19T00:00:00Z
updated: 2026-02-19T00:00:00Z
first_seen: 2026-10-03T23:09:50.514863041Z
summary: 'GPT-5.3-Codex now powers Amp''s deep mode. It’s a truly impressive model. After using it, we realized: "The coding agent is dead." Everything is changing again. With GPT-5.3-Codex, the agent is no longer the bottleneck. Our ability to tell it what to do is. In our experience, it''s better than GPT-5.2-Codex in every dimension. It still goes deep, but it''s learned when to stop. To use it: open the command palette with Ctrl-O and run the command mode: use deep in the Amp CLI, or select deep mode in the Amp editor extension''s prompt field.'
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---

GPT-5.3-Codex now powers Amp's [deep mode](https://ampcode.com/news/deep-mode).

It’s a truly impressive model. After using it, we realized: "[The coding agent is dead](https://ampcode.com/news/the-coding-agent-is-dead)."

Everything is changing again. With GPT-5.3-Codex, the agent is no longer the bottleneck. Our ability to tell it what to do is.

In our experience, it's better than GPT-5.2-Codex in every dimension. It still goes deep, but it's learned when to stop.

To use it: open the command palette with `Ctrl-O` and run the command `mode: use deep` in the Amp CLI, or select `deep` mode in the Amp editor extension's prompt field.