First of all, the documentation is incomplete. The remote debugging syntax (<server:port>@<exe>@<arch>) doesn't appear, and the behavior on Windows ABI is not documented (argument is considered a coredump if it has '.dmp' extension. Otherwise, it is considered executable).

Moreover, this syntax lacks settings for sysroot, executable (for coredump) and toolchain.

IMHO, using distinct command-line options for each setting would be much better.

Two options I had in mind are:

-debug exe=<exe>[,toolchain=<toolchain>][,server=<server:port>][,arch=<arch>][,core=<core>][,sysroot=<sysroot>]

or

-debug -exe <exe> -toolchain <toolchain> -server <server:port> -arch <arch>...

-debug <pid> can be left as it is or be added as an argument as well.