There should be a command line parameter, which outputs detailed descriptions for each available parameter.

For this purpose the --help parameter could be reused. E.g. calling

inkscape --help --verb

would list a verbose description of the --verb parameter.

When the proposal for tightening up the command line parameters[1] is implemented, the call could look like this

inkscape help query

for getting a description of the 'query' command and like this

inkscape help convert -edit

for getting a description of the -edit parameter of the 'convert' command.

Sebastian