Unlocking Agentic RL Training for GPT-OSS: A Practical Retrospective

GPT-5.3-Codex System Card

GPT‑5. 3-Codex is the most capable agentic coding model to date, combining the frontier coding performance of GPT‑5.

MCP-Universe RL: A Framework for Training MCP Tool-Use Agents via Reinforcement Learning

arXiv:2608.22167v1 Announce Type: new Abstract: Reinforcement learning (RL) has become an effective way to improve the tool-use ability of large language models (LLMs), but most existing RL framework...

gpt-oss-safeguard technical report

gpt-oss-safeguard-120b and gpt-oss-safeguard-20b are two open-weight reasoning models post-trained from the gpt-oss models and trained to reason from a provided policy in order to label content under that policy. In this report, we describe gpt-oss-safeguard’s capabilities and provide our baseline safety evaluations on the gpt-oss-safeguard models, using the underlying gpt-oss models as a baseline.

No-code personal agents, powered by GPT-4.1 and Realtime API

Learn how Genspark built a $36M ARR AI product in 45 days—with no-code agents powered by GPT-4. 1 and OpenAI Realtime API.

Welcome GPT OSS, the new open-source model family from OpenAI!

Introducing GPT-5.3-Codex

GPT-5. 3-Codex is a Codex-native agent that pairs frontier coding performance with general reasoning to support long-horizon, real-world technical work.

Agent Lightning v1.0: Towards Harnessed Agentic RL

Agent Lightning v1.0 is a lightweight framework that enables harnessed agentic reinforcement learning, where the agent harness—managing tools, context, and control flow—directly participates in model post‑training. It supports arbitrary agent harnesses and addresses challenges such as retokenization, sample merging, and advantage calculation, providing a reproducible pipeline for instruction‑following, search, and coding agents. In experiments, RL training on 6K examples improved Qwen3.5‑9B’s performance on SWE‑bench from 41.8% to 56.4%.

Building more with GPT-5.1-Codex-Max

Introducing GPT-5. 1-Codex-Max, a faster, more intelligent agentic coding model for Codex.

Update to GPT-5 System Card: GPT-5.2

GPT-5. 2 is the latest model family in the GPT-5 series.

Introducing GPT-5.2

GPT-5. 2 is our most advanced frontier model for everyday professional work, with state-of-the-art reasoning, long-context understanding, coding, and vision.

GPT-Red: Unlocking Self-Improvement for Robustness

Explore GPT-Red, OpenAI’s automated red teaming system that uses self-play to improve AI safety, alignment, and prompt injection robustness.

The builder’s guide to GPT‑5.6

Learn how startups use GPT-5. 6 to build faster, more cost-efficient AI agents with smarter model selection and new Responses API capabilities.