What's the difference between faithfulness, groundedness, and context presence?
They check three different points in the same pipeline. Context presence comes first and asks whether the information needed to answer was retrieved at all; if it wasn’t, the failure is in retrieval, before the model has written a word. Groundedness comes next and asks whether the answer actually came from that retrieved context or from the model’s own prior with the context sitting unused, which matters because an ungrounded answer can still be correct whenever the prior happens to be right. Faithfulness comes last and asks whether the answer accurately represents the source it cites, catching the case where retrieval and grounding both worked and the model still misquoted or inverted what it read.
Knowing which one fired tells you where to look. A faithfulness failure means fix the generation step; a context-presence failure means fix retrieval.