Actually, it's one less. Revel lets you run all your projects from Slack, so you don't have to spread your conversations and projects across multiple apps.
With Revel you can feature docs and tools to make sure that everyone is on the same page. Add Google docs, Jira boards, Calendars – whatever you want.
Make a project schedule and receive notifications when events are due. To-dos make sure that everyone know what their tasks are and when they are due.
Project briefs let you intro the project, show key team members and important docs. New channel members see it when they join the project channel.