Tool (Function Calling)
Also known as: Function, Function Calling, Tool Use
In one sentence
A capability that allows an AI to call external functions or APIs—like searching the web, querying databases, or running calculations.
Explain like I'm 12
Like giving AI a toolbox—it can pick the right tool (search, calculator, database) to solve your problem instead of just guessing.
In context
An AI assistant might use a weather API tool to get current conditions, a calculator tool for math, or a database tool to look up customer records.
See also
Related Guides
Learn more about Tool (Function Calling) in these guides:
Structured Output and Function Calling: Getting Reliable JSON from AI
IntermediateLearn how to get reliable, parseable JSON output from AI models using structured output, function calling, and JSON schema. Essential for production AI applications.
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AdvancedEnable AI to call APIs, query databases, and use external tools. Build agentic systems that take actions in the world.
8 min readAgents & Tools: What They're Good For (and What to Watch For)
IntermediateUnderstand AI agents that use tools to complete tasks. When they work, when they fail, and how to use them safely.
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