Allow to leave a message directly on the streams and display it to everyone looking at the same stream. Have all information in one spot when e.g. marking a stream, explaining why it was marked.

Caronte has this and it seemed mildly useful. It allows the same for services/tags too. A human description what a tag/query does would be cool. They can be stored in the state.json instead of with the stream data itself in the index files.