The purpose of a stream might not be obvious just from the title. Clearly convey what the stream is about by describing the purpose within the stream.
Steps
Add a Stream Purpose for the first time
Visit the Stream that you would like to have a description. If there hasn't been a purpose added yet, you will see the Add description in the header. Click on Add a purpose
This will open up a modal. Type in the stream purpose then press Save & Close.
You will then see the stream purpose beside the Stream header.
Edit an Existing Description
If you the stream already has a description and you would like to edit it, you can do so by clicking on Stream Settings ⚡️ in the upper right hand corner, or by clicking the stream purpose itself.
Then click on Stream details and click on the pencil icon (🖋) next to the description to make any edits.
Press save & close, and there you have it!