First, they must provide credible evidence that the invention works or is real.
One must also provide the method they used to come up with the invention.
It is often necessary that someone else can reproduce your invention.
Invention is something new. So other scientist and other orgnaizations check that it is new and no one has done it before.
These days a scientist get patents for new inventions. A patent is like a ownership badge or licence, so that anyone who uses that work can pay the scientist or has to say they used the scientists work.