Scrum Master, as Scrum Guide suggested, is responsible for ensuring Scrum is understood and enacted. Scrum Masters do this by ensuring that the Scrum Team adheres to Scrum theory, practices and rules. The Scrum Master is a servant-leader for the Scrum Team. The Scrum Master helps those outside the Scrum Team understand which of their interactions with the Scrum Team are helpful and which aren’t. The Scrum Master helps everyone change these interactions to maximize the value created by the Scrum Team.
Scrum Guide suggests that Scrum Master is a Servant-Leader. However, from so many angles, Scrum Master is not just Servant-Leader. There are so many shoes Scrum Master must wear to support the Scrum Team.
Expert Communicator: Scrum is about inspect and adapt, having conversations about how to improve each iteration. Scrum Master should be able to communicate the need to have a conversation, initiate and sustain the conversation within the decided timebox.
Coach: There is always a need for a Scrum Master to become a Team Level coach to provide guidance to the team on Scrum at the same time guide organization’s leadership with the mindset change.
Teacher: ScrumMasters posses a deep understanding of Scrum, be knowledgeable on various Agile methodologies and spark engaging conversation on how to apply Scrum.
Mentor: Building relationships and helping people achieve their best every day is the quality Scrum Master should have to serve as Mentor.
Other than above, Scrum Master is also Visionary, An agent of change, facilitator, and trainer.
Overall, Scrum Master should also be a good judge of a situation to decide what to be at what time and switch the shoes as needed to convey the thoughts to the audience.