How can I test if my powertool is getting enough electricity?
The most basic test: If the tool isn't struggling -- if the motor is maintaining its normal speed under load -- it's getting enough power for practical purposes.  If it does run into trouble, taking some load off it by cutting more slowly might help.

But in a normal building, since you aren't going to be travelling with anything huge, the odds of your needing more than 15A are low unless you're running multiple larger tools and/or there are other loads on the same circuit -- in which case, as @jack said, the breaker for that circuit should blow to keep wires from becoming a fire hazard.

(Normally. I've seen some wierdities in buildings with archaic wiring, such as a circuit that dropped from nominal 120V to something closer to 90V whenever someone used the photocopier. Still not sure how that passed inspection, but it did, repeatedly.)