Accessibility Tree

The semantic representation of a page that assistive tech — and browser-driving agents — read instead of pixels.

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

← all The Agentic Web Lexicon · .md · JSON