You’ve seen how agents can search the web, but what if you need your AI to interact with your specific company database, calculate a proprietary risk score, or even control a smart lightbulb in your house? For that, you need Custom Tools. Today, we’ll see how a simple Python decorator can bridge the gap between your local code and a LLM. 🎨 The Magic of the @tool Decorator The easiest way to create a tool in 2026 is using the @tool decorator. When you wrap a function with this, LangChain automatically analyzes your code to tell the AI: What the tool is called. What it does (based on your docstring). What arguments it needs (based on your type hints). What are Decorators in python? In Python, decorators are a powerful design pattern that allows you to modify or enhance the behavior of a function, method, or class without permanently changing its original source code. Think of a decorator as a "wrapper" that can execute code before and after the original function runs.…