Try native WebMCP in Chrome
Chrome documents an origin trial from version 149 and a local testing flag at chrome://flags/#enable-webmcp-testing. Enable the flag and relaunch for local experiments, or configure an origin-trial token for your own eligible public origin. The flag is a developer setting, not a prerequisite for using Try WebMCP’s ordinary controls.
Read the status on the playground
“Native tools registered” appears only after all five registrations succeed. “Local sandbox” means you can still use the JSON runner and visible controls. A registration error is displayed separately. The guide’s detector below reports only API presence; it cannot certify an agent connection.
Verify the actual call path
Open a playground in a supported agent environment or use Chrome’s linked Model Context Tool Inspector. Discover the page tools, invoke one, and check the trace. Calls that enter through the registered callback are labeled Native WebMCP. Clicking Run tool directly invokes the local handler, even when native registration succeeds.
If registration fails
Use a secure origin or localhost, check your browser’s current experimental support, and open the page at top level. Chrome documents origin isolation and the tools Permissions Policy. The policy defaults to self; cross-origin embedding requires additional configuration. Avoid enabling document.domain via Origin-Agent-Cluster: ?0.
Chrome: security and permissions ↗
See it in a working example.
Inspect the schema, run a call and observe the result in the page.
Open the playground