Microsoft Copilot harness at a glance
Foundry now runs the agent loop and sandbox for you: skills, MCP tools, code and file work, and subagents. It is free until December 1, 2026, then sandbox compute is billed. Crash recovery for hosted agents is now GA.
What changed with Microsoft Copilot harness
On October 28, 2026, Microsoft introduced the Microsoft Copilot harness in Foundry Agent Service, in public preview. It is a managed harness: Microsoft runs the agent loop and a sandbox, and developers supply knowledge, procedures, and tools. Agents are defined declaratively and can be built in Foundry or kept in source control next to application code.
The building blocks are reusable skills that package instructions, scripts, and resources; connected Foundry and Model Context Protocol (MCP) tools with explicit authentication and approvals; file and code work with built-in subagents; and source-controlled agent definitions. You pick a supported Foundry model. The harness must be chosen when an agent is created, switching later is not yet supported, and existing agents are unchanged.
Harness runtime is free until December 1, 2026. From then, sandbox compute is billed at $0.0994 per vCPU-hour and memory at $0.0118 per GiB-hour, and model inference and other tools are always billed at their own rates. Microsoft also made long-running resilience for hosted agents generally available: Foundry restarts interrupted work with its original input, but your app must save progress and avoid repeating actions such as sending an email twice.
Microsoft Copilot harness in numbers
Values are copied from the linked source on the date shown. They are not IA Compa measurements.
- Sandbox compute (from Dec 1, 2026)as of · Source for Sandbox compute (from Dec 1, 2026): devblogs.microsoft.com (opens in a new tab)
- $0.0994 per vCPU-hour
Why Microsoft Copilot harness matters for businesses
For agencies building client agents on Azure, this removes much of the custom loop and sandbox code. Use the free period to test, budget for sandbox hours after December 1, and design every step that touches outside systems so it can safely run again after a restart.
Put it to work: AI Agents
Sources for this story
- Introducing the Microsoft Copilot harness in Foundry Agent Service (opens in a new tab)Official
Microsoft · devblogs.microsoft.com
- What's new in Microsoft Foundry: October 2026 (opens in a new tab)Official
Microsoft · devblogs.microsoft.com
Last verified: . IA Compa summarizes public announcements for business readers. We are not affiliated with the companies mentioned. Always confirm details, pricing, and availability with the official source.
- #microsoft
- #foundry
- #azure
- #agents
- #mcp
- #sandbox
