GPT-5.5 is positioned as OpenAI's frontier model for complex professional workloads, building on GPT-5.4 with stronger reasoning, higher reliability, and improved token efficiency on hard tasks. It is designed to take messy, multi-part assignments and plan, use tools, check its work, and navigate ambiguity until a task is finished, rather than waiting for carefully staged prompts. The gains are framed as especially strong in agentic coding, computer use, knowledge work, and early scientific research, where progress depends on reasoning across context and acting over time.

The model matches GPT-5.4 per-token latency in real-world serving while operating at a higher level of intelligence, and uses significantly fewer tokens to complete the same Codex tasks. A roughly one-the cataloged API limit, with around 922K tokens of input and the cataloged API limit of output, enables large-scale reasoning and multimodal workflows inside a single system. It is aimed at practitioners who need to hand off substantial coding, research, data analysis, document, and tool-use jobs to a single model and trust it to carry the work through.