Build Hour: Agentic Tool Calling

In 2025, agents don’t just think — they run code, call tools, and complete tasks.

This Build Hour is a hands-on walkthrough of how to design agentic systems that reason and act using OpenAI’s latest APIs and SDKs. 

Ilan Bigio (Developer Experience) covers:
- What’s new in 2025: Responses API, Agents SDK, Hosted Tools, Codex, and more
- Chain of thought concepts: reasoning, tool calling, and long-horizon tasks
- Live demo: building an agentic task system to process a backlog of tickets
- Delegation: directional guidance for evals
- Live Q&A

👉 Follow along with the code repo: https://github.com/openai/build-hours
👉 Check out additional resources: https://developers.openai.com/
👉 Sign up for upcoming live Build Hours: https://webinar.openai.com/buildhours