The critical part is providing it a way to validate its work end to end. Without that, it's similar to asking a human to implement a feature with pen and paper.
Yes! Part of implementing it "one-shot" is actually a loop of planning, implementing, testing e2e on various devices and various edge-cases. It's not just writing the code, and this is not how "vibe-coding" works nowadays. It's not just writing code anymore, this is why most providers worked on their computer-use support too, not only for doing tasks, but also for being able to check and test the work they do e2e.