This paper addresses the impact of capability description on query planning in heterogeneous data integration system. Query planning covers the selection of data sources related to the query and the determination of subgoals? execution orders. In the context of capability description, we propose a framework for data sources description towards generating good feasible query plans. Our approach uses information such as the semantic correspondences between local schemas and mediated schemas and the query capability descriptions to investigate factors that provide a good foundation for query planning. Finally, the proposed approach is compared with the other capability description approaches described in the literature. The obtained results demonstrate that our approach will allow data sources to advertise their capabilities in a flexible way and help to efficiently query planning.