🚀 OpenAI Launches Codex Agent

PLUS: GPT-5 Aims For Unification

Author

The Summary AI
May 20, 2025

In partnership with

Welcome back!

OpenAI launched Codex, a powerful autonomous coding agent inside ChatGPT. Capable of writing, debugging, and testing code, it's a leap from autocomplete to hands-off engineering. Meanwhile, Microsoft revealed its own dev agent at Build 2025. Everyone’s building agents: the future of software development might be happening. Let’s unpack…

Today’s Summary:

  • 🚀 OpenAI unveils Codex agent

  • 🛠️ GitHub ships autonomous coding agent

  • 🔀 OpenAI teases unified GPT-5

  • 🖼️ Imagen 3 + Veo 2 bundled

  • 🐘 Meta delays Behemoth model

  • 📉 Prompt splits drop AI accuracy

  • 🛠️ 2 new tools

TOP STORY

OpenAI launches Codex Agent

The Summary: OpenAI has released Codex, an autonomous AI software coding agent. Codex can fix bugs, add features, test, debug and create PRs, each in an isolated cloud container preloaded with your full code repository. It’s more than a code generator as it can also run tests. Available to ChatGPT Pro, Team, and Enterprise users. Plus users will also get access soon.

Key details:

  • Codex-1 is a version of OpenAI o3 fine-tuned on coding tasks

  • Runs each task in an isolated, internet-blocked cloud container with access to your full GitHub codebase

  • Tasks are initiated with either Ask or Code mode. Ask is fast and read-only, Code can take 1-30 minutes

  • Supports multi-agent parallelism: you can spawn several agents to work independently, then review and merge the best result

  • Unlimited usage during beta with up to 60 concurrent runs per hour

  • Currently lacks persistent memory across tasks

Why it matters: Codex is an evolution from autocomplete coding to autonomous code execution. It runs agents in isolated containers and returns traceable outputs. This may redefine productivity for engineering teams, especially in large codebases with repeatable tasks. Instead of hunting through many tools, developers can send structured requests and get production-ready changes.

FROM OUR PARTNERS

Run client work smarter with AI

Get the tools, gain a teammate

  • Impress clients with online proposals, contracts, and payments.

  • Simplify your workload, workflow, and workweek with AI.

  • Get the behind-the-scenes business partner you deserve.

MICROSOFT

GitHub ships Copilot Coding Agent

The Summary: GitHub Copilot’s new coding agent was unveiled at Microsoft Build 2025, alongside a wave of AI tools across the Microsoft ecosystem. The agent, built on similar principles as OpenAI Codex, can autonomously take on coding tasks like adding features and fixing bugs. It’s Microsoft’s take in the fast-heating race to build coding agents.

Key details:

  • Can autonomously fix bugs, add features, and extend tests

  • Operates in GitHub cloud environment, booting VMs, cloning repos, and building PRs

  • Available on GitHub.com, Mobile, and CLI

  • Users warned about potential runaway costs in current version

  • Microsoft Build 2025 also introduced Copilot Tuning, the Agent Factory for custom model deployment, and NLWeb, a natural language interface for the web

Why it matters: Everyone is racing to build AI coding agents. GitHub has the home-court advantage of hosting most code already, and can integrate features directly into the familiar workflows developers use every day.

FROM OUR PARTNERS

Stay informed without the noise

Seeking impartial news? Meet 1440.

Every day, 3.5 million readers turn to 1440 for their factual news. We sift through 100+ sources to bring you a complete summary of politics, global events, business, and culture, all in a brief 5-minute email. Enjoy an impartial news experience.

OPENAI

OpenAI aims to end model switching with GPT-5

The Summary: In a Reddit AMA, OpenAI confirmed that GPT-5 will focus on doing everything current models can do, but better, and as a single system. That means less model switching between GPT-4o, o3, o4-mini, Codex, and Operator, and more of the feeling that you’re using a single coherent AI assistant.

Key details:

  • GPT-5 will unify many OpenAI tools into a single seamless system

  • Operator, the AI screen agent, will be updated soon and could become a very useful tool on user desktops

  • OpenAI downplayed benchmarks, favoring real-world task performance to measure progress, like an AI that just gets a specific job done

Why it matters: Too many models hurt usability and productivity. OpenAI wants GPT-5 to fix that. Instead of asking users to pick the right model or tool for the task, the new system will figure it out automatically. That means smarter defaults and fewer decisions. It also means ChatGPT becoming less of a text generator and more of a general purpose agent.

TOOLS

🥇 New tools

  • Inkr - Transcribe, quick notes, and search smarter in real time

  • MirWork - Job interview practice partner from any job listing

That’s all for today!

If you liked the newsletter, share it with your friends and colleagues by sending them this link: https://thesummary.ai/