In common with many state of the art semantic technologies, there is a lack of comprehensive, established evaluation mechanisms for semantic search tools. In this paper, we describe a new evaluation and benchmarking approach for semantic search tools using the infrastructure under development within the SEALS initiative. To our knowledge, it is the first effort to present a comprehensive evaluation methodology for semantic search tools. The paper describes the evaluation methodology including our two-phase approach in which tools are evaluated both in a fully automated fashion as well as within a user-based study. We also present and discuss preliminary results from the first SEALS evaluation campaign together with a discussion of some of the key findings.