> I still don't understand what a "tool" is

"A .NET tool is a special NuGet package that contains a console application. You can install a tool..."

https://learn.microsoft.com/en-us/dotnet/core/tools/global-t...

it's actually very similar to the node.js / NPM equivalent, which came first:

https://docs.npmjs.com/downloading-and-installing-packages-g...