Check-EternalBlue is a simple script (VBS) which checks whether your PC is patched against EternalBlue, the NSA-uncovered exploit used by WannaCry ransomware.
There's no real interface, just one message explaining that the script is going to access your list of installed updates, and another stating whether it thinks your PC is patched.
The script ran without difficulty on our test PC, but that won't be the case everywhere. VBS files are often used by malware, and it's possible your security settings and software may block them.
Check-EternalBlue didn't always work for us, claiming that a fully-updated system was "NOT patched against EternalBlue". As patches can be rolled up in different update numbers, our guess is it doesn't cover them all.
Still, we're reasonably sure that you will be able to trust an "is patched" verdict. And if you're the technical type, check out the code, too. It's straightforward and can easily be adapted to check for other updates.