It's okay to use more than two words so long as the extra words are adjectives describing the noun. For example, I have a sharp knife, so it's okay to say GET SHARP KNIFE. What you really need to test for is the use of pronouns (such as GET IN BOAT) and a second noun (such as STAB TROLL WITH SHARP KNIFE). I've noticed that even if you enter a second noun, it gets ignored, so maybe it doesn't matter.
I'd also like to know how to use multi-word input for further down the track.