Those are PowerShell cmdlets - and follow PowerShell verb-noun naming convention. There is a finite set of "approved" verbs (though you can use your own) representing the "actions" you can perform against a resource (the noun part).

From within a PowerShell console I can "add" a lot of things. Try typing

    gcm -verb add

from a PowerShell console (gcm is alias for Get-Command and the command above will list all commands where "Add" is the verb).

They are using the same syntax as NuGet- the Visual Studio package manager console.

I take it you don't have much experience with powershell, which is fair enough. Most people don't.

Long story short: These are "Commandlets", commands provided to your PowerShell-session through extension-modules.

The PowerShell convention for command-names are Verb-Noun, like for instance Get-DiskImage or whatever, so it makes sense that OneGet builds on these.

Descriptive names are good (to some limit). You can maybe add something else (a remote repo? Something else), or maybe it isn't unthinkable that Add-X will eventually be a feature. You can always make an alias "inst" so it's better to keep the underlying command long and descriptive.

Also: these should be edited with autocomplete.