GPT-5.5 Pro

GPT-5.5 Pro sits at the top of OpenAI's GPT-5.5 family as a high-capability tier built for deep reasoning and accuracy on complex, multi-step work. OpenAI's launch materials frame the line as its smartest and most intuitive yet, with the Pro variant specifically tuned for long-horizon problem solving, agentic coding, and precise execution across multi-step workflows. The model matches the per-token latency of its predecessor while operating at a higher level of capability and using fewer tokens to complete equivalent tasks, according to OpenAI's own comparison. Independent coverage reinforces the positioning, describing GPT-5.5 Pro as aimed at messy, multi-part tasks where sustained reasoning, tool use, and self-checking matter more than raw speed.

In practice, GPT-5.5 Pro is a strong fit for workflows that combine long documents, code, and research: it accepts both text and image inputs, produces text outputs, and exposes a very wide context window that comfortably holds book-length material plus extensive conversational history. OpenAI highlights concrete gains in agentic coding, computer use, knowledge work, and early-stage scientific research, and third-party reporting notes the same rollout pattern across ChatGPT Plus, Pro, Business, and Enterprise tiers alongside Codex. The combination of structured output, tool calling, and attachments support makes it well suited to enterprise pipelines that need an orchestrating model to plan, call tools, verify results, and carry long tasks to completion, with the Pro tier chosen when reasoning depth outweighs cost sensitivity.