What it is
The job it was built for, and the job it is not for.
GPT-4.1 is a general-purpose flagship model tuned for three jobs in particular: following detailed instructions precisely, handling real-world coding tasks, and reasoning over very long inputs. OpenAI positions it as an improvement on GPT-4o across those areas. It is not a dedicated reasoning model and not a small, cheap classifier, so high-volume routing or trivial extraction work belongs elsewhere.