Rubber Duck in GitHub Copilot CLI now supports more models

Rubber Duck, the cross-family review agent in GitHub Copilot CLI, is now available using a Claude-powered critic agent when your session is using a GPT model. For sessions using Claude as their orchestrator, we’ve upgraded the GPT model used to seek a second opinion.

What’s new

• Rubber Duck for GPT sessions: When you’ve selected a GPT model as your orchestrator, and /experimental is enabled, Copilot will dispatch a Claude-powered Rubber Duck agent to provide a second opinion. The same second-opinion benefits (architectural catches, subtle bugs, and cross-file conflicts) now apply to GPT-driven sessions.

• Stronger reviewer models for Claude sessions: Claude orchestrator sessions can now pair with GPT-5.5 as the Rubber Duck model for more effective second opinions.

To try it, run copilot and ensure /experimental on is toggled.

To learn more about how Rubber Duck combines model families to improve Copilot CLI’s performance, read our recent blog post.

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