Faithfulness

Faithfulness asks whether the retrieved context supports the claims in an answer. Many evaluation systems use it as a synonym for groundedness.

Tiny example

Context: Returns are accepted for 30 days.
Answer:  Returns are accepted for 30 days without a receipt.

The first claim is supported. “Without a receipt” is not, so the answer is not fully faithful.

Do not confuse it with

• Answer relevance: does the answer address the question?
• Correctness: does it match trusted truth or a reference answer?
• Retrieval relevance: do the passages relate to the question?

LangSmith’s RAG evaluation guide separates these comparison pairs explicitly.¹

FDE note

A faithful answer can repeat a stale or incorrect source. Groundedness is not proof that the underlying document is true or current.

Footnotes

1. LangChain, “Evaluate a RAG application”. ↩