{
  "dataset": "glossary",
  "record": {
    "id": "tool-use",
    "term": "Tool Use",
    "category": "core",
    "short_def": "An LLM's ability to call external functions — search, code execution, APIs — by emitting a structured request the host executes.",
    "long_def": "The model does not run the tool itself; it outputs a tool call, the host runs it and returns the result, and the model continues. Tool use (also called function calling) is what turns a chat model into an agent.",
    "see_also": [
      "ai-agent",
      "mcp",
      "agentic-loop"
    ],
    "etymology_origin": {
      "value": null,
      "verify_status": "verify-against-primary-at-build",
      "source_hint": "https://platform.openai.com/docs/guides/function-calling — popularised as 'function calling' by OpenAI (June 2023); no single coiner for the broader 'tool use' sense"
    },
    "related_to": [
      "ai-agent",
      "mcp",
      "agentic-loop"
    ],
    "contrast_with": "Unlike plain text generation, tool use emits a structured, machine-parseable call that the host actually executes — the model proposes the action; the host performs it.",
    "example": "OpenAI shipped function calling for tool use in its API in June 2023; MCP later standardized how those tools are discovered and described across vendors.",
    "source": "https://platform.openai.com/docs/guides/function-calling",
    "status": "active",
    "why_it_matters": "Tool use is the mechanism by which an agent acts on your site; exposing clean, well-described tools (e.g. via MCP) is what makes a site actionable to agents.",
    "sameAs": [],
    "bridge_entity": "protocols/capability/mcp",
    "last_verified": "2026-06-15",
    "md_twin": "/glossary/tool-use.md"
  }
}