Cluster Health - Drilling Deeper: Finding Problematic Indices - clarifications

[vkatsikaros]

elasticsearch-definitive-guide/500_Cluster_Admin/20_health.asciidoc does a great job in introducing the health endpoint and some first debugging in case something is wrong.

Later on it says:

Once you know the index that is having problems, other APIs that we discuss in this chapter will tend to be more helpful.

I was wondering if this point could provide more details on troubleshooting and what these other APIs might be.