Tool for adding custom search engines to browser. It can be also used to make aliases for address bar without any browser extension.
add-search-engine "Facebook Conversations" https://www.facebook.com/messages/t/{searchTerms}
The page for adding search engine will be opened in your default browser. Add the search engine (corresponding button will appear in search bar) and set keyword (for example, fb) for it.
Now you can open conversation with a person typing the following in address bar:
fb <nickname>