It's pretty clear from the laws the First and Second Congress passed that they had an even broader definition of "broad powers" than we do today. (And by the way, the Federal Papers have no legal authority in US law. They're interesting from a historical perspective because they documents an attempt by one politician to sway the opinion of the general public, but they don't form any part of the corpus of American jurisprudence.)
I'm well aware that the Federalist Papers aren't law. The reason why I mentioned them is that they come from the party that was anti-Articles, pro-Constitution and pro-strong federal government. So reading them gives you an idea of what they meant by "strong federal government", and what they considered to be out of bounds.
And all of those broad powers they wanted the government to have, were explicitly written into the text of the Constitution. Sometimes it was deliberately vague, like the Commerce Clause (although if you showed our modern jurisprudence on that to people who wrote it, they would be horrified). And in the Federalist Papers, there are several instances where some bit in the Constitution is explained as, "yes, this is rather broad, but the government needs it for real world reasons". But it is always enumerated.