The wrong extension is one of the most expensive agency mistakes. Installation is quick; migrating away after six months of data and configurations is painful. Evaluate first.

1. Update frequency and changelog quality. Updated regularly? Changelogs descriptive or vague? 6+ months without an update is a risk.

2. Support responsiveness. Check the WordPress.org support forum. How quickly do developers respond? Are answers helpful? For premium plugins, submit a pre-sale question.

3. Block Checkout compatibility. If it touches checkout — test it with Block Checkout specifically on staging. Don’t assume.

4. Active installs and reviews. 100K+ installs with 4.5+ stars means community-tested. 200 installs means early-adopter risk.

5. Source. Woo Marketplace = reviewed by Woo, lowest risk. WordPress.org = community-reviewed, free. Third-party sites = highest variability. For client stores, Marketplace is safest.