The indications of cast metal inlay are all except
Inlays

An inlay can be defined as a restoration which has been constructed out of mouth from gold, porcelain or other materials and then cemented into the prepared cavity of a tooth.

Indications

The cavity's width does not exceed one-third the intercuspal distance.
Strong, self-resistant cusps are there.
Minimum or no occlusal facets  present and if present, are confined to the occlusal surfaces only.
The tooth is not to be used as an abutment for a fixed or removable prosthesis.
Occlusal or occluding surfaces are not to be changed by the restorative procedure.

MDS Prep Bytes (Cast Restoration – Inlay)
The cavity’s width exceeds ⅓ the intercuspal distance
Strong, self-resistant cusps present
Occlusal surfaces are not to be changed
The tooth is not to be used as an abutment