How do I know my agency is actually doing anything?

The short answer

Read the change history in your own Google Ads account. Every edit is timestamped and you own it.

This is the single best check available and almost nobody uses it. Tools > Change history shows every modification, who made it and when. An account with no changes for three weeks is an account nobody is running.

Beyond that: a written weekly update naming what changed and why, and daily performance you can read without a call.

More in answers, or read the full FAQ.