Rubric Labs developed an AI-driven email assistant, Cal.ai, designed to streamline calendar management through natural language processing and integration with Cal.com's API. Utilizing an OpenAI functions agent through LangChain, the system processes user requests sent via email, converting them into actionable scheduling tasks. This is achieved by employing a combination of fine-tuned GPT models and dynamic structured tools, enabling the execution of CRUD operations on user calendars. The architecture involves parsing incoming emails, verifying them, and using a chat model to interact with various tools to fulfill user requests. The system emphasizes consistent and reliable interaction by using a low-temperature setting on the GPT-4 model to minimize output variability. Once the agent processes a request, it sends the user a response via email, facilitated by services like Sendgrid. This approach showcases the efficacy of combining language models with structured tools to handle natural language input effectively, positioning AI agents as powerful solutions for managing structured data tasks.