Recently, numerous authoring tools for Augmented Reality (AR) have been proposed, in both industry and academia, with the aim to enable non-expert users, without programming skills, to scaffold educational AR activities. This is a promising authoring approach that can democratize AR for learning. However, there is no systematic analysis of these emerging tools regarding what AR features and modalities they offer (RQ1). Furthermore, little is known as to how these emerging tools support teachers' needs (RQ2). Following a twofold approach, we first analyzed a corpus of 21 authoring tools from industry and academia and formulated a comprehensive design space with four dimensions: (1) authoring workflow , (2) AR modality , (3) AR use, and (4) content and user management. We then analyzed two workshops with 19 teachers to understand their needs for AR activities and how existing tools support them. Ultimately, we discuss how our work can support researchers and designers of educational AR authoring tools.