Augmented reality (AR) has been incorporated into the educational context for years. Numerous studies have demonstrated the effectiveness of AR in different disciplines, learning styles, and learning environments. However, few studies have focused on the problem of generating AR applications in authentic educational contexts. In this study, an AR learning resource authoring tool called WebART was designed and developed to help teachers with no prior programming experience create and share AR learning resources. This study collected feedback and opinions on WebART from 51 K-12 teachers through questionnaires and interviews. Multiple linear regression was used to measure the relationships between teachers' intentions to use technology and the user experience of the proposed WebART tool. The questionnaire results revealed that multiple variables in teachers' intentions are predictive of user experience. Interview results showed that teachers had a positive attitude toward the AR learning resources authoring tools inspiring novel ways of teaching and learning.