Word for "that which shows the reality behind a phenomenon"?

Solution 1:

Trying to be creative, such a tool might be called an "endoscope".

Since such a tool elucidates, one could coin "elucigen" as something that generates elucidation.

You could say that those tools are revelatory:

making people aware of something that they did not know before
a revelatory insight

A related word is enlightening.