Tool use

Tool use is an AI agent reaching outside its own text to do something in the real world, searching the web, running a calculation, calling an API, reading a file. The model recognises it needs information or an action it can't produce from memory, picks the right tool, uses it, and folds the result back into its reasoning. Function calling is the technical plumbing; tool use is the broader capability it enables.

For a founder this is the line between a clever writing assistant and a worker. An agent with tools can check live data, take actions in your systems, and complete a task end to end rather than just advising. It matters because it changes what you can safely delegate. More tools mean more reach but also more ways to cause harm, so you scope each tool tightly, give read-only access where you can, and add approval steps on anything irreversible like sending or deleting.