A good dictionary is an indispensable companion of a Sanskrit student (and of scholars). There are many popular Sanskrit-English dictionaries like those of Monier Williams, VS Apte, AA Mac Donell. But they could be of use only to those who know English. The great work known as Vachaspatya is a standard work and is very useful for scholars. But until a well edited edition of this work comes out, it could not be of much help to even an average Sanskrit student.
When the author of Samskrita Sabdartha Kaustubha compiled it, there were only three Sanskrit Hindi dictionaries available for the Hindi speaking students. They were all too small for much practical use, so the author compiled the present work with the hope of answering the needs of Hindi speaking Sanskrit students who are studying Sandkrit in a college or schoof or privately. Samskrita Sabdartha Kaustubha is designed to be an adequate guide to a knowledge of Sanskrit words. It contains as many explanations and details as are permitted by the limited space at the disposal of the compiler.