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Addendum to GPT-5 system card: GPT-5-Codex
OpenAI just released GPT-5-Codex. Here's what dynamic thinking effort means for your engineering workflow.
The KeyNews take
Why it matters
OpenAI is releasing a specialized variant of GPT-5 optimized for agentic coding tasks, featuring adaptive compute allocation based on task complexity. This signals a shift toward task-specific model variants and dynamic inference as a competitive capability.
The key facts
5 to knowGPT-5-Codex is a specialized variant of GPT-5 optimized for agentic coding
Dynamic thinking effort allocation based on task complexity
Responds quickly to simple queries/small tasks, allocates longer thinking for complex tasks
Released as addendum to GPT-5 system card
Published September 15, 2025
Go to the source
OpenAI Blogopenai.com
Publisher excerpt: 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…