Description from extension meta
Search docs on MDN in 3 steps
Image from store

Description from store
1. Ctrl+M to open the MDN Search Bar (or click the extension icon)
2. Type what you want to search on MDN. The result will be shown in a new tab
3. If the first result of the list is what you are looking for, simply press "tab" and "enter" (otherwise, just click the document you want)