Microsoft’s Copilot makes Anthropic’s Claude and OpenAI’s GPT team up

Microsoft is now using both OpenAI's GPT and Anthropic's Claude in tandem within its Copilot Researcher agent. A new 'critique' feature has GPT draft responses while Claude reviews them for accuracy, completeness, and citation integrity — a multi-model approach that outperforms either model alone on the DRACO benchmark (57.4 vs. 50.4 for Claude in Deep Research mode). Microsoft is also bringing Anthropic's Cowork tool (long-running multi-step agents for knowledge workers) into Copilot under the name Copilot Cowork, now available in the M365 Frontier early-access program. The move reflects Microsoft's strategic bet that its value lies not in owning frontier models but in the enterprise data and trust layer it provides around them, while simultaneously deepening its dependency on external model providers.