Agents are autonomous systems capable of executing complex tasks with minimal instructions, and the article explores how LlamaIndex.TS's built-in agents can be used to achieve specific goals. It demonstrates building a simple agent for calculations using LlamaIndex, requiring the installation of the llamaindex package and an OpenAI key. The article provides examples of creating sum and multiply functions, setting up tools for these functions, and using an OpenAIAgent to perform calculations. Additionally, the article describes using agents with personal or private data to answer questions, focusing on processing Dan Abramov's essays by loading documents into a local vector store index for querying relevant data. It explains setting up a query engine tool and an OpenAI agent to access this data, enabling the agent to answer questions about Abramov's work experience. The article concludes by discussing the potential of autonomous agents in enhancing workflows and automation, although fully autonomous systems are still a work in progress with the help of Large Language Models (LLMs).