Addendum to GPT-5 system card: GPT-5-Codex

OpenAI released an addendum to the GPT-5 system card introducing GPT-5-Codex. This version is specialized for code generation and programming tasks. It enhances developer productivity by providing more accurate and context-aware code completions.

ArchiveLaunch

Signal trust

Single sourceEarly signal

PublishedMonday, September 15, 2025 at 2:00 AMSep 15, 02:00 AM

FreshnessArchive

Story ID#295

Back to feed Original report

Original article excerpt

Server-side extracted preview paragraphs from the original source.

This addendum to the GPT-5 system card shares a new model: GPT-5-Codex, a version of GPT-5 further optimized for agentic coding in Codex. GPT-5-Codex adjusts its thinking effort more dynamically based on task complexity, responding quickly to simple conversational queries or small tasks, while independently working for longer on more complex tasks.

GPT‑5‑Codex is a version of GPT‑5 optimized for agentic coding in Codex. Like its predecessor, codex-1, this model was trained using reinforcement learning on real-world coding tasks in a variety of environments to generate code that closely mirrors human style and PR preferences, adhere precisely to instructions, and iteratively run tests until passing results are achieved.

Opening the briefing

Addendum to GPT-5 system card: GPT-5-Codex

Original article excerpt