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Chrome 149 Opens WebMCP Origin Trial, Letting Sites Expose Tools to AI Agents

July 10, 2026 at 14:39 EDT

AI Agents
Software Dev & Coding
Open Source

Google has opened an origin trial for WebMCP, a proposed standard that lets web pages expose structured tools to AI agents, starting in Chrome 149, and explained how to implement it at Google I/O Connect in Berlin. Two APIs, Declarative and Imperative, let developers upgrade existing sites for agents with relative ease.

Chrome 149 · WebMCP Origin Trial

A Standard Way for Web Pages to Hand AI Agents Real Tools

WebMCP lets sites expose structured JavaScript functions and HTML forms to a browser's built-in agent — so agents call tools directly instead of scraping the DOM or reading screenshots, keeping the human UI intact.

~5s

Task completion with WebMCP

30–60s

Old DOM-scraping approach, high failure rate

APIs: Declarative & Imperative

Speed to complete an agent task

Lower is better — each block ≈ 10 seconds

up to 60s

DOM scraping

~5s

WebMCP tools

Imperative API

navigator.modelContext

Flexible JavaScript control — form filling, navigation, and state management.

Declarative API

Annotations on HTML forms

Turns existing forms into agent tools with minimal changes.

WebMCP vs MCP — complementary, not competing

WebMCP

Web apps inside the browser — same tab, same session.

MCP

Server-side resources — external databases and APIs.

Welcomed

DevTools panel: list, invoke & debug tools
Lighthouse "Registered WebMCP tools" audit
Live demos & end-to-end deploys shared

Open questions

Refactoring burden on complex sites
Needs a browser tab & direct visit to discover tools
Confirmation dialogs urged for purchases

Timeline: Origin trial spans roughly Chrome 149–156 on desktop and Android, with an equivalent trial in Microsoft Edge — a stable rollout is planned for Chrome 157.

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