Recent research suggests that architectural knowledge, such as design decisions, is important and should be recorded alongside the architecture description. Different approaches have emerged to support such architectural knowledge (AK) management activities. However, there are different notions of and emphasis on what and how architectural activities should be supported. This is reflected in the design and implementation of existing AK tools. To understand the current status of software architecture knowledge engineering and future research trends, this paper compares five architectural knowledge management tools and the support they provide in the architecture life-cycle. The comparison is based on an evaluation framework defined by a set of 10 criteria. The results of the comparison provide insights into the current focus of architectural knowledge management support, their advantages, deficiencies, and conformance to the current architectural description standard. Based on the outcome of this comparison a research agenda is proposed for future work on AK tools.