How to Build Your First AI Agent with Claude API: A Step-by-Step Guide Most developers who “build AI agents” are really just calling a chat completion endpoint in a loop. That is not an agent. A real agentic AI system perceives its environment, decides which tools to use, acts on those decisions, and observes the results before deciding what to do next. The Claude API makes this loop surprisingly straightforward to implement. This guide walks you through building one from scratch, in Python, with working code you can run today. ...