Enable WebMCP in Chrome
Chrome provides a local testing flag for WebMCP. The change takes effect after the browser relaunches.
chrome://flags/#enable-webmcp-testingOpen the WebMCP flag
Paste chrome://flags/#enable-webmcp-testing into Chrome’s address bar and press Enter.
Set the flag to Enabled
Chrome opens the WebMCP testing flag directly. Choose Enabled from its dropdown.
Relaunch Chrome
Use the Relaunch button at the bottom of the flags page so Chrome restarts with WebMCP enabled.
Return and check again
Open this page again after Chrome relaunches. The support check above should now find document.modelContext.
If WebMCP is still not detected
A missing API does not always mean the browser lacks WebMCP. Check the environment before treating the result as final.
Relaunch Chrome completely
Changing a flag requires a browser relaunch. Refreshing the tab alone does not apply it.
Use HTTPS or localhost
The WebMCP API is only exposed in a secure context. A regular HTTP page will not pass the check.
Check the page context
Cross-origin iframes need the tools permission, and pages that disable origin isolation cannot use WebMCP.
Update Chrome if the flag is missing
Flag availability follows Chrome development. Use an up-to-date Chrome build and check Chrome Status for the current rollout.
The support check looks for document.modelContext.registerTool. It does not detect an AI agent, verify tool permissions, or confirm that the current page registered tools.
Try a WebMCP-enabled page
Once the check passes, open a demo or developer tool and inspect the structured actions it exposes.
Chrome WebMCP FAQ
Does Chrome support WebMCP?
Chrome offers WebMCP through an origin trial starting in Chrome 149 and through the chrome://flags/#enable-webmcp-testing flag for local development and testing.
How do I enable WebMCP in Chrome?
Open chrome://flags/#enable-webmcp-testing in Chrome, set WebMCP for testing to Enabled, and relaunch the browser. Then return to this page to check whether document.modelContext is available.
Why was WebMCP not detected after I enabled the flag?
Make sure Chrome fully relaunched, reload the page, and use HTTPS or localhost. WebMCP can also be unavailable when origin isolation is disabled or when a permissions policy blocks tools in an embedded frame.
Does a successful check mean an AI agent is installed?
No. The check only confirms that this page can see the WebMCP browser API. It does not detect an AI agent, confirm tool permissions, or prove that a page has registered any tools.