For whole release as well as feature or story there are conditions of satisfaction which helps to define the story acceptance. Development team can’t successfully deliver the business wants unless conditions of satisfaction for a story are agreed up front.
The Customer team should “speak with one voice”, if team is getting different requirement from different stakeholders, team needs to push back and put off the story until there is a firm list of business satisfaction conditions. The best way go understand customer’s requirements is to talk with the customer face to face. These conditions are based on key assumptions and decisions made by customer for a story coming with a high-level acceptance criteria for each story.
Discussing conditions of satisfaction helps identify risk and increases the team’s confidence in writing and correctly estimating all of the task that are needed to complete the story
Book: AGILE TESTING A Practical Guide for Testers and Agile Teams
Book: Effective Software Project Management by Robert K. Wysocki