for a small genset to start is an induction motor; you'd find one of those in a table saw and some air compressors (Compressors are the hardest loads of all to start with a small genset). The rest of the tools (drills/grinders/skilsaws) you're likely to encounter use universal motors, which aren't quite as bad.
The first thing is to ignore the 'surge' rating as smoke and mirrors, unless they give a time with the rating. . . 5 minutes, 30 seconds, whatever. . . look in the owners manual for that sort of info. Manuals are usually findable online. . . .
Even if they DO provide a time for the the "surge" rating, it is effectively the 'overload' capacity of the gen, and you don't want to depend on that for any reason. It's useful only to give some idea of the ruggedness of the unit; and to give you an idea if it can manage to start a large inductive load.
For less than $1k, surge capacity in a genset is effectively a non-issue. (as in, it's all lies.)
Next, let's dispose of this 'watts' nonsense- thats a useful number for incandescent light bulbs and maybe PA equipment, and not much else. What you REALLY want to know is the rated current; and compare that with the tools you'll be using. Which means that the advertizements aren't likely to be useful; you'll need to go look at the builder's plate on the generator to get the straight dope. Have a look at your tools before you go, and think about what combinations you're likely to use together. . . have the numbers written down when you go shopping.
I like to have a 25% de-rating factor on my gen (which is to say, I total up my maximum forseeable load currents, then multiply by 1.25, and that gives the rating I'll be looking for when I go shopping.) I could go into why that number vs some other, but it boils down my experience with the foibles of inductive loads.(transformers and induction motors again).
