Response API Transforms AI Agents

In OpenAI’s latest Build Hour, “Build Hour: Responses API,” Steve Coffey from the API Engineering team delves into the intricacies of OpenAI’s flagship Response API, showcasing how it can revolutionize the development of AI agents and applications. The video, hosted on October 14, 2025, demonstrates diverse functionalities such as built-in tool usage, preserving reasoning tokens across API requests, and integrating multimodal workflows with GPT-5. Steve effectively communicates the significance of the Response API as a faster, more cost-efficient solution compared to the previous chat completions API, especially for long, tool-intensive AI rollouts. While the discussion appreciates the seamless migration to the Response API, it raises curious points about potential challenges developers might face when transitioning their existing applications. Moreover, the video explores practical applications through live demos, illustrating scenarios like agentic capabilities within an OpenAI engineer simulator and how the API can handle complex task interactions using multiple tools. Although the Response API offers growth and expansion of AI capabilities through persistent reasoning and multimodal inputs, some concerns linger about its initial adaptation and the learning curve for developers new to agentic models. Nonetheless, the flexibility and forward-thinking design of the Response API serve as a pivotal advancement in enhancing AI development.