{
  "dataset": "glossary",
  "record": {
    "id": "accessibility-tree",
    "term": "Accessibility Tree",
    "category": "knowledge-memory",
    "short_def": "The semantic representation of a page that assistive tech — and browser-driving agents — read instead of pixels.",
    "long_def": "Derived from semantic HTML and ARIA and specified by the W3C Core Accessibility API Mappings, it exposes roles, labels and structure. Agents that drive a browser act through this tree, which is why accessible markup doubles as an agent interface: one investment, two audiences.",
    "see_also": [
      "webmcp",
      "agent-experience"
    ],
    "etymology_origin": "A construct of browser/user-agent accessibility APIs, normatively specified by the W3C in the Core Accessibility API Mappings (Core-AAM) and WAI-ARIA, developed by the W3C ARIA Working Group.",
    "related_to": [
      "webmcp",
      "agent-experience",
      "agentic-loop"
    ],
    "contrast_with": "Unlike the DOM, which describes a page's full markup and presentation, the accessibility tree exposes only its semantics — roles, labels and states — which is what a browser-driving agent (and a screen reader) actually consumes.",
    "example": "A browser-driving agent like Operator acts through the accessibility tree's roles and labels (per the W3C Core Accessibility API Mappings) rather than parsing pixels.",
    "source": "https://www.w3.org/TR/core-aam-1.1/",
    "status": "active",
    "why_it_matters": "The accessibility tree means accessible markup IS an agent interface — one investment in semantic HTML/ARIA serves both assistive tech and browser-driving agents.",
    "sameAs": [
      "https://developer.mozilla.org/en-US/docs/Glossary/Accessibility_tree"
    ],
    "bridge_entity": "agent-readiness",
    "last_verified": "2026-06-15",
    "md_twin": "/glossary/accessibility-tree.md"
  }
}