Huh? Both Anthropic and OpenAI have computer use tools. I frequently just tell the models to test their own work. I'm a little paranoid so I only grant access to one window and make that window VMware Workstation.

You combine it with /goal. I usually set a goal like "Complete the application defined in goal.md as written. Then test it end to end autonomously using Compter Use. Record all issues discovered during testing in a to-do. Then fix the issues in the to-do. Repeat testing until no more issues are discovered."