Retrieval · L2 · 20 min
Failure modes
Learn in five minutes
- Missed retrieval: the passage exists and was not returned.
- Empty notes: the passage does not exist and the model should refuse.
- Distractor: a similar passage is the wrong one.
- Stale note: the text is old. Date the note.
- Lab 06 is a small ablation of keyword versus a naive neighbor. Confirm before you treat it as your corpus.
Label the failure before you change the prompt. A prompt rewrite does not fix a missed index.
Visual
Name the failure
- Take a wrong answer.
- Ask: was the right passage returned?
- If no, the failure is retrieval.
- If yes, the failure is reading or the instruction.
- Write one label.
Quiz
Ecosystem
- Ablation
- Turning one piece off to see what changes.
Sisters: Search indexes, Embeddings, Rerankers, Citations.
A voice agent and a chat agent can share the same note index.
The capstone answers only from notes you are allowed to use.
Config
- Write the goal in one sentence.
- Name the input and the allowed output.
- Save the trace next to the result.
Troubleshooting
- The answer looks fluent and is wrong. Check whether a source passage actually contains the claim.
- The loop never stops. Set a step cap and stop when the tool result repeats.
Sources and go deeper
- Lewis and co-authors, Retrieval-Augmented Generation for Knowledge-Intensive NLP Tasks, 2020 paper last checked 2026-10
- OWASP Top 10 for Large Language Model Applications community last checked 2026-10
- Retrieval-augmented generation — Wikipedia wikipedia last checked 2026-10