protologue

Function Calling

Also called tool use, tool calling.

Function calling, or tool use, is a model capability in which the model outputs a structured request to invoke a developer-defined function with arguments, which the application executes and returns as a result to the model.

Description

Tools are usually described to the model with a name, a natural-language description, and a JSON Schema for parameters. Clear tool descriptions function as prompts in their own right and strongly affect when and how tools are used.

Sources

  1. Anthropic (2024). Tool use with Claude.
  2. Patil et al. (2023). Gorilla: Large Language Model Connected with Massive APIs.

Cite this entry

Protologue. (2026). Function Calling. In Protologue: A Taxonomy of Prompting and LLM Techniques (v1.0.0, PTL-0060). https://protologue.com/t/function-calling/

BibTeX
@misc{protologue_function_calling,
  title = {Function Calling},
  author = {{Protologue}},
  year = {2026},
  howpublished = {Protologue: A Taxonomy of Prompting and LLM Techniques, v1.0.0},
  note = {Entry PTL-0060},
  url = {https://protologue.com/t/function-calling/}
}

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