Tool use
Tool use is a model’s ability to call external functions — searching, running code, querying a database — and incorporate the results into its answer.
Whether a tool gets called correctly depends mostly on its description. Descriptions should say what the tool does, when to use it, when not to, and what it returns, because that text is the entire basis for the model’s decision.
Related terms
- Function calling
- Function calling is a model feature that returns a structured request to run a named function with specific arguments, instead of returning prose.
- AI agent
- An AI agent is a language model given tools and a goal, which decides for itself which actions to take and in what order until the goal is met.
- MCP (Model Context Protocol)
- MCP is an open protocol that lets language models connect to external tools and data sources through a common interface, rather than a bespoke integration per tool.
More on retrieval and agents
See the full glossary, read the guides, or put it into practice in the prompt builder.