Aussie AI

Function Calling

  • Last Updated 30 August, 2025
  • by David Spuler, Ph.D.

Function calling is where LLM architectures access an external module via a function call to retrieve extra data, perform calculations, or trigger an action. It is also known as "tool usage" by the LLM, as distinct from the reverse meaning in the use of LLM tools by AI developers.

Types of function calling include external integrations for features such as:

  • Data retrieval (e.g., search the internet, search real estate listings database, etc.)
  • Computation tools (e.g., clocks, calculators, arithmetic)
  • Action tools (e.g., the LLM calling out to "agents" that can send an email, make a booking, etc.)

Related areas of LLM research include:

Research on Function Calling

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