For a given report and dimension, you will need to pass 1 or more appropriate filters. Filters are query string params that filter the data view returned (i.e. reduce the number of rows in the result set).
For a given dimension, there are mandatory filters (that must be passed in every request) - as well as optional filters (that you can add at your own discretion).
This section contains a list of all supported filters for the Campaign Summary Report - and their data types.
The supported filters (query params) vary, depending on your chosen dimension. See Supported Dimensions.
For an overview of concepts, see Dimensions, Filters and Columns.