{
 "id": "https://redfinchadvisory.com/lexicon/tool",
 "slug": "tool",
 "prefLabel": "Tool",
 "altLabel": [
  "Tool use",
  "Tool calling",
  "Function calling"
 ],
 "hiddenLabel": [],
 "definition": "A single action, such as running a task or a function, that an agent can call.",
 "scopeNote": "Where a tool lives depends on where it can be reached, not who built it. A centrally hosted tool that others can use is part of the stack. A local tool scoped to one person's harness, like an advanced developer's local MCP server, is part of that harness. An agent's permission to use a tool is always harness. Building a central tool is a stack contribution; wiring your agent to it is harness configuration.\n\nToday tools are mostly central and shared; local, harness-only tools are the exception. Watch: personal agents may start creating tools on the fly for one person or task, which would shift part of the tool layer into the harness.",
 "tier": "explain",
 "group": "Connections and systems",
 "broader": [],
 "narrower": [
  "https://redfinchadvisory.com/lexicon/computer-use",
  "https://redfinchadvisory.com/lexicon/code-execution"
 ],
 "related": [
  {
   "id": "https://redfinchadvisory.com/lexicon/model-context-protocol",
   "type": "related"
  },
  {
   "id": "https://redfinchadvisory.com/lexicon/agent-skill",
   "type": "confused"
  }
 ],
 "links": [
  {
   "id": "https://redfinchadvisory.com/lexicon/agent",
   "label": "is called by an",
   "direction": "out"
  },
  {
   "id": "https://redfinchadvisory.com/lexicon/agent-gateway",
   "label": "is governed by",
   "direction": "out"
  },
  {
   "id": "https://redfinchadvisory.com/lexicon/connector",
   "label": "comes packaged in a",
   "direction": "out"
  },
  {
   "id": "https://redfinchadvisory.com/lexicon/mcp-server",
   "label": "offers",
   "direction": "in"
  }
 ],
 "modified": "2026-10-21",
 "markdown": "https://redfinchadvisory.com/lexicon/tool.md",
 "inScheme": {
  "id": "https://redfinchadvisory.com/lexicon",
  "version": "1.0",
  "currentAsOf": "2026-10-21"
 }
}