Sierra, an AI customer service agent company, has revamped its engineering interview process by eliminating traditional coding and algorithm tests. The new approach involves three stages: Plan, Build, and Review. Candidates first lead the product concept, then independently develop a product using AI tools within two hours, and finally present their work, discussing technical decisions and deployment strategies. Additionally, Sierra has replaced coding tests in phone screenings with system design interviews, emphasizing the importance of scaling applications for production. A new debugging interview is also being piloted, where candidates improve a medium-sized codebase. The company aims to focus on identifying candidates' strengths and matching them with suitable roles. Feedback has been positive, with candidates successfully using AI to create interactive demos during interviews.