Hi @Fabian_Schreiber & @Dylan_Keys,
We are currently building a project brief API endpoint. We anticipate it will be released in November.
In addition to having API parity with the Asana web product, another motivation for releasing this endpoint is to give developers a preview of what rich text is going to look like on other Asana assets in the future. I recommend that all Asana developers (and particularly those that use html_notes or html_text) read and follow this topic about the upcoming (and potentially breaking) addition of new rich text formats to various Asana objects. We will be posting to this thread when we release the project brief endpoint.