Sage is an MCP server designed to enhance code understanding, review, and implementation planning through the use of large language models. It automatically selects between OpenAI's O3 and Google's Gemini 2.5 Pro based on token count, embedding referenced filepaths recursively to provide a comprehensive context to the model. This enables developers to obtain second opinions, detailed code reviews, and robust implementation plans from AI models capable of handling vast amounts of code accurately, improving code quality and development efficiency.