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A field guide to grounded answers

RAG lets an AI open the right pages before answering.

Retrieval-augmented generation searches a prepared knowledge source for relevant evidence, places that evidence in context, and asks the model to answer from it.

01 · Mental model

An open-book answer, not a memory test.

The analogy

A researcher receives a question, finds the most useful pages in a library, and keeps those pages open while composing an answer.

The reality

A retriever selects relevant text chunks. The model generates from the question plus those supplied passages.

02 · Two-time system

Prepare once. Retrieve per question.

INDEXUploadCollect trusted source files.
INDEXChunkSplit documents into useful passages.
INDEXEmbedRepresent meaning for similarity search.
QUERYRetrieveRank passages against the question.
QUERYGenerateAnswer with selected evidence.

Retrieval happens before generation. It changes the model’s working material; it does not rewrite the model itself.

03 · Try retrieval

Different question, different open pages.

0.94Visitor hours

Galleries close at 5:00 PM Tuesday–Sunday.

0.72Holiday schedule

Special closures supersede normal hours.

04 · What gets computed

Meaning becomes searchable position.

The north entrance has a step-free ramp.
Oversize bags must be left at coat check.
The galleries close at 5:00 PM.

Embeddings help rank semantic similarity. Metadata filters can narrow the candidates by source, date, category, or access policy.

05 · RAG is not a truth machine

Evidence can still be missing, stale, or misread.

RECALLDid retrieval find it?

Poor chunks or vocabulary mismatch can hide the right passage.

QUALITYWas the source reliable?

Retrieving outdated material grounds the answer in outdated material.

FAITHFULNESSDid the answer follow it?

The model can still overgeneralize beyond the supplied evidence.

06 · Good boundaries

Show your working set.

Preserve source identity, return citations when possible, separate retrieved text from instructions, enforce access controls before search, and say when the evidence does not answer the question.

07 · Keep this model

Find small. Read close. Answer carefully.

INDEXPrepare knowledge

Chunk and organize authoritative sources.

RETRIEVESelect evidence

Find the few passages most relevant now.

GENERATECompose answer

Use the evidence inside the model’s context.