Building Agentic AI Apps With Claude: Tools, Loops, and Production Patterns

Most AI apps are wrappers: user sends a message, LLM responds, done. Agentic apps are different -- the AI takes a sequence of actions, uses tools, and produces a result the user couldn't get from a single prompt. Here's how to build one that actually works in production. What Makes an App "Agentic" An agentic app has at least three properties: Tool use: The AI can call external functions (search, read files, make API calls) Multi-step execution: The AI decides what to do next based on previous results Goal-directed: The AI is working toward an outcome, not just answering a question A simple example: "Research the top 5 competitors for my SaaS product and summarize their pricing." Non-agentic: User manually searches each competitor, pastes pricing into a doc, asks Claude to summarize. Agentic: Claude searches each competitor, extracts pricing from each page, compares them, writes the summary. The Core Loop Every agentic app runs the same basic loop: 1. Receive goal from user 2. Plan nex