This is Part 7 of my series on the Microsoft Agent Framework. You can read the original post over on lukaswalter.dev . When words are not enough So far, our agent can answer questions, stream responses, remember conversations, reduce chat history, and receive dynamic context. But it still has one major limitation: it can only talk. An LLM does not know your current application state by default. It cannot query your database, calculate values from your domain model, or place an order unless your application exposes that capability. This is where tools come in. A tool is a controlled C# function that the model can request during a run. The model does not execute arbitrary code. It can only call the functions you explicitly provide. The flow looks like this: The user asks something that requires application logic. The model requests a tool call instead of producing a final answer. The framework invokes the matching C# method. The result is passed back to the model. The model uses that result to answer the user.…