I'm trying to use the Validate Metadata tool, as described at About validating metadata—Help | ArcGIS for Desktop but am finding that it doesn't work correctly.
I open the Description tab for the layer, then choose the Validate button. This opens up the Validate Metadata geoprocessing tool with all the values pre-filled.
Upon hitting the OK button the tool runs, and reports that all tests have passed. This is the same whether or not the metadata is actually valid (as reported by the Edit tab) and regardless of the Metadata Style chosen under > ArcCatalog Options.
The Validate Metadata geoprocessing tool then re-opens with all inputs pre-filled. The output file is never created.
I've verified this on two computers, running Windows 7 and ArcGIS 10.2.1 and 10.3.1