Smarts C++ API question

We are having trouble invoking a Server Tool using the Smarts C++ API.

We are using the operation "invokeSync" of an instance of class ICS_ActionManager sending the arguments:
- "target" as a sm_objref_t
- "action_id" as a sm_string_t
- "parameters" as a sm_anyval_array_t

So far it works for tools without parameters (user prompts) where the "parameters" argument is sent empty, but we can not find any documentation on which values to send inside the "parameters" sm_anyval_array_t , in which order and of which type. For example if the Server Tool is expecting 2 parameters, the most intuitive option would be to send two sm_string_t values inside the "parameters" sm_anyval_array_t but it wont work and fails returning the error "Remote server error".

Thanks.