The query rewriting service uses the Sense Analysis Service to first obtain the senses of the search query. Therefore many of the concepts described on that page are relevant.
Rewriting Options: Discusses how an application can control the rewrites generated by selecting an appropriate recipe and using the API parameters.
Rewriting Recipes: Depending on the context, an application may wish to obtain not only equivalent paraphrases but more general or more specific. This document describes the recipes available.
Providing Sense Annotated Input: Describes how applications can provide sense annotations to the rewriting API. Useful when the senses are already known.