Why Agents Need Tools › The Agent's Role: Deciding When and How to Use Tools

Tools expand the agent's capabilities, while the agent supplies the intelligence needed to use them. It still needs to:

Understand what you're asking. If you say "What's the weather like?", the agent needs to recognize this requires current information, not just general knowledge about weather patterns.

Decide which tool to use. If the agent has access to a calculator, a weather API, and a calendar, it needs to choose the right one for your question.

Interpret the tool's output. If the weather API returns {"temp": 72, "conditions": "partly_cloudy"}, the agent needs to translate that into a natural response: "It's 72 degrees and partly cloudy."

Combine multiple tools if needed. Some questions require using several tools in sequence. "What should I wear for my meeting tomorrow?" might require checking the calendar (when is the meeting?), checking the weather (what will conditions be like?), and then reasoning about appropriate attire.

The language model is still the brain of the operation. Tools are just extensions of its capabilities, like how your smartphone extends your memory and computational abilities.