Microsoft puts the Copilot harness into Foundry Agent Service public preview
Microsoft released a managed Copilot harness in Foundry Agent Service with an agent loop, sandbox, skills, authenticated tools, approvals, files, code execution and built-in subagents. A new Copilot Studio paper reports 10.8- and 22.1-point pass-rate gains over its Standard harness on two tested models while cost-weighted tokens fell 15% to 21%.
Why it matters: The paper supplies measured evidence that harness design can change task success, cost and recovery even when the model is held constant. That makes orchestration, caching and tool-loop behavior first-class evaluation variables rather than invisible product…