What happens if we swap AI brains?

A developer tested whether the AI model or the interface tool matters more for coding effectiveness by swapping Anthropic's Claude model with Google's Gemini model inside Claude Code using an open-source tool called claude-code-router. Through debugging experiments, Claude significantly outperformed Gemini at exploration and planning tasks, requiring only one interaction versus six for the same bug fix. However, detailed prompts dramatically improved Gemini's performance, suggesting both model fine-tuning and interface prompts influence coding assistant effectiveness.