Fundamentals

Tool Use

Tool use is the broader concept where LLMs leverage external capabilities. This includes function calling, API access, database queries, web searches, and code execution. Tools extend LLM capabilities beyond text generation. A model with tool use can research the web, perform calculations, check inventory, or retrieve documents. Building effective tool use requires clear API definitions, good error handling, and thoughtful prompt engineering. Multi-step tool use (where calling one tool provides data for the next) enables complex workflows. Tool use is fundamental to building agentic systems.