Add WebMCP to a page

Register page tools through document.modelContext and know which browsers and agents will call them today. The shared crawl found a WebMCP hint on 25 of 7,545 top-10,000 home pages. First step: Feature-detect document.modelContext. Last step: Test in a browser with the origin trial or flag enabled.

Steps

1. Feature-detect document.modelContext.
2. Call registerTool with name, description, input schema and handler.
3. Set allow="tools" on cross-origin iframes that need it.
4. Test in a browser with the origin trial or flag enabled.

What the sources say

• The draft API is document.modelContext with registerTool(), getTools(), executeTool() and a toolchange event. (github.com, read 4 November 2026)
• Cross-origin iframes need Permissions Policy allow="tools". (github.com, read 4 November 2026)
• TypeScript definitions ship as webmcp-types on npm. (github.com, read 4 November 2026)
• nekuda's FAQ (October 2026): Chrome and Edge test WebMCP in an origin trial, Brave behind a flag, Firefox and Safari have none, and Gemini in Chrome and Claude for Chrome do not use WebMCP tools yet. (webmcp.com, read 4 November 2026)
• Ora's 30 Sep 2026 post demoed a WebMCP tool returning an MCP App View, requiring chrome://flags/#enable-webmcp-testing. (ora.ai, dated 30 September 2026, read 4 November 2026)

How common it is

The crawl reads each home page's initial HTML for a WebMCP hint. It found one on 25 of 7,545 home pages in the top 10,000 and on 59 of 3,393 on Ora's leaderboard. A hint in the HTML is not a working tool; check in a browser that registers it.

Domains with a hint

agent-ready.dev, agentready.org, allbirds.com, astronomer.io, august.com, awaytravel.com, bristlehealth.com, browserless.io, casper.com, chiikawamarket.jp, circle.so, circleci.com, cloudflare.com, cookiebot.com, cratejoy.com, curacel.co, daisonet.com, dartai.com, deepnight.ai, discoverpilgrim.com, ecoflow.com, elementor.com, everlane.com, evernote.com, feverup.com, flaviar.com, flexfits.com, getbinks.com, getcargo.ai, getcargo.io, getlago.com, givelegacy.com, glossier.com, gymshark.com, heypocket.com, hostinger.com, hypeandvice.com, isitagentready.com, linksys.com, lionpose.com, lucy.co, lusbrands.com, matagora.com, monday.com, mynextderma.com, nanit.com, naturallclub.com, nishatlinen.com, onrender.com, ora.ai, pages.dev, playably.ai, popl.co, primitive.dev, quickchat.ai, rarebird.coffee, render.com, rungroundcontrol.com, saya.pk, shipreal.dev, shoplocale.com, shoptiques.com, signnow.com, socksoho.com, soteriskin.com, soundboks.com, telnyx.com, theessential.com, usenourish.com, usercentrics.eu, usergems.com, usetaiga.com, vendah.com.br, webmcp.com, whitepages.com, whoosh.com, workers.dev, wpastra.com, wyndly.com, wyze.com, wyzecam.com, youspot.com, zbiotics.com, zellbury.com, zenrows.com.