Breaking

Chrome 149 Opens WebMCP Origin Trial, a Web Standard for AI Agents

June 26, 2026 at 15:04 EDT

AI Agents
Software Dev & Coding
Open Source

A new web standard called WebMCP, led by Google and Microsoft, has entered a public origin trial in Chrome 149. The proposal lets AI agents call functions on existing websites directly as structured "tools," with participation announced via the Chrome for Developers blog.

Chrome 149 · Origin Trial · Web Standards

WebMCP: Websites Can Now Hand AI Agents a Set of Tools

A proposed web standard led by Google Chrome and Microsoft Edge engineers lets sites declare JavaScript functions and form elements as structured "tools" that in-browser AI agents can discover and invoke — instead of reverse-engineering screenshots and the DOM.

Ways agents act today: screenshots, DOM, Accessibility Tree — all inferred

Single agent request can complete multi-step operations

Extra server load — runs client-side in the tab

How an agent reads a page — before vs. with WebMCP

Screenshot

DOM parse

A11y Tree

BEFORE

Infer UI · heavy tokens · fragile

Declared tools
desc + JSON Schema

WITH WebMCP

Explicit actions · fewer tokens · reliable

The core API · navigator.modelContext

Each tool = a natural-language description + a JSON Schema. Sites expose form fills, button actions and in-app functions to any agent.

Declarative

HTML form annotations

Imperative

JavaScript API

Model-agnostic

Gemini · Claude · ChatGPT

Seen as advantages

Multi-step tasks in one agent request
No screenshots — fewer tokens, faster
Polyfills (gui-agent) work on any site today
Possible "AI-ready" baseline, like robots.txt

Open questions

W3C community-group draft — not yet a standard
Not confirmed for stable Chrome
Cross-browser support still immature
Existing sites must add the work to adopt

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