There are two common UEFI Shells available. The first is the older EFI Shell (see the TianoCore EdkShellBinPkg) and the second is the UEFI 2.0 Shell (See theTianoCore ShellBinPkg.) Most current UEFI implementations seem to use the older shell.
In the EFI Shell, you invoke “help utility” to get help text for a particular utility. You can also do “help utility -b” to display the help text screen by screen. Just using “help” produces a sorted list of all available shell commands.
In the UEFI Shell 2.0, when you invoke “help utility” to get help text for a particular utility, only a single summary line is displayed. You must invoke “help utility -v” or “help utility -verbose” to get the full help. Help text for any shell utility is “help utility”. You can also do “help utility -v -b” to display the help text screen by screen. Not all commands have help text available for them. Just using “help” produces a unsorted list of all available shell commands.
Note that the ShellBinPkg UEFI Shell 2.0 does not appear to work on many current UEFI implementations. It either hangs or crashes. For example, it fails on the Lenovo T430 laptop which supposedly is a UEFI 2.31-compliant (SecureCore) implementation by Phoenix Technologies.