This paper introduces AutoMOOSE, an open-source agentic framework designed to orchestrate the complete simulation lifecycle of multiphysics phase-field materials modeling through natural language prompts. The system employs a five-agent pipeline where an Input Writer coordinates six sub-agents, while a Reviewer autonomously diagnoses and corrects runtime failures without human intervention. A modular plugin architecture allows integration of new phase-field formulations, and a Model Context Protocol server exposes ten structured tools for external client interoperability. The framework is validated on a copper grain growth benchmark, demonstrating its ability to generate valid MOOSE simulation input files.