Some apps only chat

A simple chat app has a small job. It sends messages to Rufus and displays the text he produces.

Other apps surround Rufus with ways to search, run code, or work with files. These are called tools.

An app that lets a model choose tools and use their results is often called an agentic app. The surrounding program is sometimes called an agent harness.

The model can be the same. The agentic app gives it more ways to act.