The Agent Loop: Plan, Act, Observe, Repeat

The agent loop is usually drawn as four boxes in a circle. The boxes hide the only interesting part, which is what exactly gets appended to the message list and in what order. Here is the whole thing as code. The shape Send the conversation. If the reply contains tool calls, execute them, append their results, and send the conversation again. If it does not, you have an answer. That is the entire control structure — the loop body is a single branch, and every framework in existence is wrapping…