Answer:Having commitment on the requirements by all involved stakeholders is important as it ensures that you are developing a product that your customers need and are willing to pay for. The project/team also needs to be committed to do whatever they can to deliver the product with the specified functionality.
You don’t need to have commitment on everything when you start a project. It is unfeasible, too expensive and takes too long to get. To support that teams can start developing a product, make sure that the stakeholders agree on the priority: What needs to be delivered first, what do we need now? That should give sufficient commitment to warrant investing time and money.
Agile teams use product backlogs to manage their requirements. Product owners prioritize the user stories. To enable delivering products with sufficient quality agile teams need to have user stories that are ready at the start of a sprint.
Teams can use a Definition of Ready (DoR) to check the user stories. A DoR states the criteria that a user story should meet be accepted into an iteration.
Some useful resources to make your own Definition of Ready are:
The INVEST principle by Bill Wake
10 Tips for writing good user stories by Roman Pichler
The book User Stories Applied by Mike Cohn
The book 50 quick ideas to improve your user stories by Gojko Adzic
Using a Definition of Ready on InfoQ
Exercise cards for defining your DoR and DoD by David Koontz
