Answer: demand assurances of performance from stonework
Explanation: In simple words, assurance of performance refers to the written guarantee from the service provider that the service will be preformed as per the fixed guidelines.
These assurances is very common in contracts which requires specific performance or performance from a specific person or an entity.
These contracts can be used in the court of law in case any conflict between the related party happens in future, thus it provides satisfaction to the paying party to some extent.