one year on
OpenAI releases Responses API and open-source Agents SDK for building AI agents
New tools let developers create custom agents with web search, file search, and computer use capabilities, replacing the Assistants API.
OpenAI today released the Responses API and an open-source Agents SDK, giving developers tools to build AI agents that can search the web, scan files, and control computers. The Responses API replaces the Assistants API, which will be sunset in the first half of 2026.
The API provides access to GPT-4o search and GPT-4o mini search models for web browsing with citations, a file search utility that OpenAI says will not train on user files, and the Computer-Using Agent (CUA) model in research preview for automating mouse and keyboard actions. The CUA can also be run locally on enterprise systems. The open-source Agents SDK offers integration, safety, and monitoring tools as a follow-up to last year’s Swarm framework.
OpenAI’s API product head Olivier Godement told TechCrunch that “to scale an agent is pretty hard, and to get people to use it often is very hard.” The launch follows CEO Sam Altman’s January declaration that 2025 is the year AI agents enter the workforce. Skeptics in developer forums noted that GPT-4o search still scores only 90% on the SimpleQA benchmark and that the CUA model remains unreliable for automated tasks. The question hanging over the announcement is whether these tools will deliver autonomy or just more polished demos.
OpenAI's API product head told TechCrunch that demos are easy but scaling and frequent use are hard, and he hopes to bridge the gap between demos and products this year.
One year later — open only if you can handle spoilers
By mid-2026, the Responses API saw moderate adoption among enterprises, but most agent workflows remained heavily supervised. The Assistants API sunset was delayed to late 2026 after developer backlash. The term 'year of the agent' became a running joke in AI circles.