How VAST teams actually use these tools
VAST work usually starts with one simple question: did the player get a valid response fast enough to play something real? From there the path branches quickly. Sometimes the XML is malformed. Sometimes the wrapper chain is too deep. Sometimes the tag is valid but the media file or player environment is the real problem.
That is why this cluster is built around sequence, not just tool count. Teams usually inspect the tag first, then trace wrappers, then check latency, then look at error meaning or creative fit. The tools are grouped that way because that is how real triage tends to happen when a placement is failing under time pressure.
If you are doing launch QA, use these tools to catch risky chains before traffic ramps. If you are in incident mode, use them to shrink the problem quickly and write a cleaner escalation to the SSP, ad server, exchange, or player owner.