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Function calling lets an AI model invoke external tools, APIs, or code using structured, machine-readable arguments instead of free-form text. It underpins agents, coding assistants, and other systems that need a model to take real actions — searching the web, querying a database, running a script — rather than just describe them. This hub tracks how model providers implement the capability and how developers use it to build more reliable AI applications.
Function calling lets AI models like ChatGPT and Claude reach beyond their training data — searching the web, running code, or querying a database — by calling tools an app defines.
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