What is function calling (tool use)?
An LLM's ability to call software functions, such as "check availability" or "create booking", during a conversation.
Function calling (tool use), explained
Function calling is what lets a voice agent act, not just talk: it checks a calendar, writes to a CRM or sends a payment link while the caller is on the line.
Each function is a small, well-defined action with clear inputs, such as a date, a time and a phone number. Keeping functions narrow makes the agent's actions predictable and easy to audit.
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Related terms
- Large language model (LLM)An AI model trained on large amounts of text that can understand requests and generate human-like replies.
- CRM integrationConnecting a voice agent to a customer relationship management system so call details and outcomes are saved automatically.
- WebhookAn automatic message one system sends to another when something happens, such as "new lead submitted".
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