GitHub Copilot CLI adds Rubber Duck for second-opinion AI suggestions

GitHub has expanded Copilot CLI with Rubber Duck, a new feature that generates alternative code suggestions by consulting different AI model families within the tool.

What is Rubber Duck?

Rubber Duck operates as a built-in second-opinion system for Copilot CLI. When developers request code suggestions or explanations in the terminal, Rubber Duck can provide an alternative perspective by leveraging a different model family than the primary suggestion engine. This gives users multiple approaches to the same problem without switching tools or contexts.

The feature is accessible directly from the CLI, maintaining the integrated workflow developers expect from GitHub's AI assistant.

Model Family Approach

The implementation reflects a deliberate architectural choice: rather than relying on a single model, GitHub's approach uses multiple model families to generate suggestions. This strategy acknowledges that different AI models have different strengths—some may excel at certain coding patterns, optimization techniques, or explanatory approaches.

GitHub has not disclosed which specific models or vendors power each model family in this implementation.

Developer Experience

The Rubber Duck feature integrates into Copilot CLI's existing workflow. When users request code suggestions, they can access the alternative perspective without manual intervention or additional configuration.

This addresses a common developer need: when the first suggestion doesn't feel right, having an immediate alternative saves context switching and maintains flow state. Rather than copying code to a separate chat interface or switching to the web version of Copilot, developers can iterate within their terminal.

What this means

GitHub is positioning Copilot CLI as a multi-model platform rather than a single-model tool. This approach distributes the technical risk of relying on one model while providing users with practical optionality. The Rubber Duck feature signals that GitHub views second opinions as core to code generation—not a luxury feature, but a workflow necessity. For developers already using Copilot CLI, this represents expanded capability at no apparent additional cost.