Microsoft said on October 28 that it is making the Microsoft Copilot harness available through Microsoft Foundry, extending a runtime it says already powers Copilot across its own products. The company framed the move as a way for developers and enterprise customers to build agents that can reason, use tools and complete longer-running tasks.

With the Copilot harness, Microsoft runs the agent loop and sandbox, with governance and optimization built in from the start. Developers bring the instructions, skills, tools and model choice, and Microsoft says the platforms remain open and interoperable, so other harnesses and frameworks can still be brought in.

Microsoft says the SDK is available to download, or the harness can be run in the cloud, all managed by Foundry. Because agents built in Foundry can run on the same harness Microsoft has adopted internally, its continuous harness improvements should benefit those agents too.