Definition
Quality Score is Google Ads' 1-to-10 diagnostic rating of a keyword, based on expected click-through rate, ad relevance and landing page experience. It's a guide to ad quality, not a direct input to the auction.
MegaMCP glossary32 terms
Explained
Low components point to the fix: low expected CTR suggests weak ad copy or poor query match; low ad relevance suggests the ad doesn't match the keyword's intent; low landing page experience suggests a slow or off-topic page.
Microsoft Ads shows its own 1-to-10 quality score for keywords as well.