Applications published in the Slack Marketplace must meet Slack's formal listing and review requirements. These requirements extend beyond functional API behavior and cover presentation, privacy, support, security, and overall user experience. Slack requires Marketplace listings to include high-quality visual presentation, including a recognizable, high-resolution application icon. The listing must also provide descriptive information explaining what the application does, which problems it solves, and how users interact with it inside Slack. Slack's current Marketplace guidelines separately define both short and long descriptions. Most importantly, Marketplace applications must provide a clearly accessible privacy policy explaining how third-party data is collected, used, retained, transferred, or deleted and how users can make privacy-related requests. A private single-workspace application does not undergo Slack Marketplace listing review. Merely implementing bot functionality does not trigger these listing requirements either. An unlisted publicly distributed app can be installed across workspaces using OAuth, but it is not automatically subject to the complete Marketplace listing presentation process. The original question uses the older term Slack App Directory. Slack's current official terminology is Slack Marketplace. This belongs to Distribute Your App, specifically Marketplace submission and listing requirements.