To add to @andrew.rybka answer, the "Parameter table" action works for the cases when you need to capture task parameters within the workflow at runtime.
Obtaining task parameters from task configurations is currently not supported out of the box. However, since task configurations are just XML files, you can try extracting them by parsing XML. In this topic, there is a sample workflow that does it: Easymorph Server Command (List ServerTask Parametervalues) - #4 by rebmanna