I'm a heavy user of Things3 for organizing my tasks, and because I've been using it since v1.0, my habits about putting it to work are rather ingrained. I've been using the macOS Share Extension to add items to Things for a very long time. Unfortunately, when you're sharing a web page from Safari, that only sends the URL to Things, so then you have to type the title of the page.
Having some time on my hands lately, I thought I'd cook up a Keyboard Maestro macro that solved this problem. But while investigating Things' x-url support, I discovered there's a feature I've never used that provides this exact functionality (and more).
In Things3 Preferences > Quick Entry turn on the Autofill option and install the helper app, as explained in the pane. It's great!