OpenAI Inc. announced on Wednesday the launch of its upgraded reflective generative pre-trained transformers (GPT) o3 and o4-mini to the Application Programming Interface (API) and ChatGPT after a slight delay.

"For the first time, our reasoning models can agentically use and combine every tool within ChatGPT ... Critically, these models are trained to reason about when and how to use tools to produce detailed and thoughtful answers in the right output formats, typically in under a minute, to solve more complex problems," OpenAI wrote, describing the o-series as "models trained to think for longer before responding."

In its detailed statement, the company explained that o3 is the "most powerful reasoning model" and recommended it for "complex queries requiring multi-faceted analysis and whose answers may not be immediately obvious." Meanwhile, o4-mini was described as focused on "fast, cost-efficient reasoning."