Microsoft Agent Framework at Build 2026: Agent Harness, Hosted Agents, and CodeAct

Microsoft Agent Framework Blog·high signal

At Build 2026 (June 2-3, San Francisco), Microsoft expanded its Agent Framework with an agent harness pattern, skills support in Foundry Toolboxes, procedural memory, Voice Live integration, and CodeAct for code-driven tool execution. Hosted agents in Foundry Agent Service add sandboxed sessions, persistent state, and filesystem access, with GA expected by early July 2026. This consolidates Microsoft's AutoGen + Semantic Kernel merger into a production multi-agent platform competing directly with the OpenAI Agents SDK and Claude Agent SDK.