GPT‐5.3‐Codex

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.