New tools and features in the Responses API

Today, we’re adding new built-in tools to the Responses API—our core API primitive for building agentic applications. This includes support for all remote Model Context Protocol (MCP) servers⁠(opens in a new window), as well as tools like image generation⁠(opens in a new window), Code Interpreter⁠(opens in a new window), and improvements to file search⁠(opens in a new window). These tools are available across our GPT‑4o series, GPT‑4.1 series, and OpenAI o-series reasoning models. o3 and o4-mini can now call tools and functions directly within their chain-of-thought in the Responses API, producing answers that are more contextually rich and relevant. Using o3 and o4-mini with the Responses API preserves reasoning tokens across requests and tool calls, improving model intelligence and reducing the cost and latency for developers.

We’re also introducing new features in the Responses API that improve reliability, visibility, and privacy for enterprises and developers. These include background mode⁠(opens in a new window) to handle long-running tasks asynchronously and more reliably, support for reasoning summaries⁠(opens in a new window), and support for encrypted reasoning items⁠(opens in a new window). 

Since releasing the Responses API in March 2025 with tools like web search, file search, and computer use, hundreds of thousands of developers have used the API to process trillions of tokens across our models. Customers have used the API to build a variety of agentic applications, including Zencoder⁠(opens in a new window)’s coding agent, Revi⁠(opens in a new window)’s market intelligence agent for private equity and investment banking, and MagicSchool AI⁠(opens in a new window)'s education assistant—all of which use web search to pull relevant, up-to-date information into their app. Now developers can build agents that are even more useful and reliable with access to the new tools and features released today.