<!--IssueSummary start--> <details> <summary> Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards. </summary> - [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=366467) </details> <!--IssueSummary end--> We need a full definition for the 'last_activity_at' attribute in the Projects API so that we can accurately document what specific actions users can take in their projects to maintain activity for our internal team members understanding. Today we have the [SaaS Free User Efficiency - Data Retention Policy](https://internal-handbook.gitlab.io/handbook/product/saas-efficiency/data_retention_policy/) in the internal handbook for our team members. legal has requested that we add a full definition for the 'last_activity_at' attribute.