Microsoft-Decision-1 is available through Microsoft Foundry and OpenRouter, according to the company. Microsoft built the model by post-training Qwen3.5-9B and said it plans to rebase it on other models, including Microsoft AI (MAI) and OpenAI models.
Model targets specific decisions
Decision-1 supports yes-or-no judgments, choices among predefined options, ratings, and rubric-based assessments of AI responses and agent actions, Microsoft said. Developers can use its outputs to classify inputs, rank work, verify responses, or determine the next action in an AI agent workflow.
Unlike a general-purpose LLM, which can generate explanations and other natural-language content, decision models return probabilities for the available answers. Microsoft said its Decision-1 model can also evaluate multiple decisions in parallel within a single request.
