The purpose of the working agreement is to ensure the Agile Team shares responsibility in defining expectations for how they will function together and enhance their self-organization process.
Working agreement are guidelines that define how groups want to work together, and what they want in the working environment and from each other to feel safe and free to learn, explore and discover.
Work agreements are the set of rules/disciplines/processes the team agrees to follow without fail to make themselves more efficient and become self managing aspect of scrum. These agreements help the team build a shared understanding of what it means to work as a team.
The key benefit of working agreements is their enforceability. Since everyone has agreed to follow the rules, enforcing those rules becomes less awkward when infractions occur. For example, my team has a rule that everyone should be attentive during meetings and stay off their phone.