This paper presents an autonomous conversational mobile robot Butsukusa that can describe its own observations and internal states during patrolling tasks. The proposed robot can observe the surrounding environment using the recognition module for objects, humans, environment, localization, and speech and then move autonomously around an indoor living space. Interaction skills via language are required for the robot to perform in such human-centered spaces. To investigate a better communication protocol with users, we evaluate various language generation patterns based on different observations and interaction patterns. The evaluation results indicate that the importance of describing the robot's observation results and internal states, as well as the necessity of an appropriate description, depends on the situation.