GPT-5.3 adds Instant System Card capability for chat prompts

AI Impact Summary

GPT-5.3 introduces a new Instant System Card capability for chat sessions, enabling quicker application of system prompts. This can streamline how organizations initialize model behavior across deployments and reduce setup latency for new sessions. Teams should verify client libraries support the new capability and plan for any changes in how system prompts are defined and passed to the GPT-5.3 API.