An experimental feature may be disabled on a page for a number of reasons. Web developers should have an easy way to figure out why features are disabled on their pages.

Currently, an error message is output to the console on the first attempt to access a feature that is disabled. That message could be missed, or lack enough detail for the web developer to debug the problem. Further, with planned changes to JavaScript binding support, it may not be feasible to output console messages.

For usability, there should be info on origin trials available in devtools. This should include:
- List of trial tokens found for the current page/context, with details:
  - Valid vs invalid for enabling feature
  - Reason if not invalid
  - Token version
  - Contents: origin, feature name, expiry
- Tool to test validity of a given token, i.e. allow copy/paste of token to try for current page