For agent fact-recall, reach for grep before vector retrieval — but tune the harness, not just the retriever

arXiv·high signal

A PwC empirical study across Chronos plus the Claude Code, Codex, and Gemini CLI harnesses found literal grep generally beats vector retrieval on LongMemEval fact-recovery, yet overall accuracy swings more on which harness and tool-calling style you use than on the retrieval method itself. Also test inline vs. file-based tool results separately — the same grep tool scores differently depending on whether the model reads results inline or from a file. Practical move: default to grep for fact recall, then A/B your harness and tool-result delivery as first-class variables instead of assuming the embedding model is the bottleneck.