Microsoft unveils Copilot harness, a layer for managing agents across 20+ models and users' own keys
Prepared by Sintelligent with the help of SI. Published in SI: . Updated: .
Microsoft is making its agent software independent of any single model: users can choose from many.
According to Microsoft, the Copilot harness gives agents instructions, context, an execution environment and controls; it supports MCP, agent skills and plugins, and works with "20+ frontier models" and users' own keys. The harness underlies Copilot Code, Copilot Studio, the GitHub Copilot app, the CLI and VS Code; it is available as a managed service in Microsoft Foundry, and the SDK can be downloaded from GitHub. The company says it ported the harness to Rust and explains: "If the model supplies the intelligence, the harness is everything around the model."
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