Multi-hop RAG and agentic RAG
Words made simple
A few useful meanings before you read the explanation.
- RAG
- Find relevant information first, then give it to a model to help answer the question. The answer is only as reliable as the information and checks used.
- API
- A way for one piece of software to ask another for data or an action. A claims API might return the current status of a claim.
- Retrieval
- Finding and fetching information that is useful for the current question.
More words from this lesson
- Agent
- An application that uses a model to choose its next action within defined limits. It can use tools and continue through several steps.
- Deterministic
- Following steps or rules defined by code. The model does not decide which step should run next in a deterministic workflow.
- Latency
- How long a request takes to return a result. Lower latency usually means a shorter wait for the user.
- Dependency
- A library or package that your application relies on. Compatible versions help the application run as expected.
Overview
- Multi-hop RAG retrieves information in dependent steps: one finding determines the next search.
- Agentic RAG lets a bounded agent choose retrieval tools or decide whether another search is needed.
- A fixed two-step retrieval workflow can be multi-hop without being an open-ended agent.
Why this matters
Some answers require connecting customer, product, and document information rather than one search.
An everyday example
An employee identifies your policy type, opens its handbook, then checks a related endorsement.
A technical example
policy lookup → endorsement IDs → retrieve applicable endorsement → explain effect.
How it works
- Establish required information
- Retrieve first evidence
- Determine missing links
- Retrieve next evidence within budget
- Track sources
- Stop or escalate.
Architecture and flow
Question → first lookup → dependent search → evidence sufficiency check → answer.
The insurance assistant example
A policy's base coverage is modified by an endorsement stored separately.
When to use it
Dependent evidence questions and mixed search/API requirements.
When to avoid it
A single known FAQ lookup does not need an agent or repeated searches.
Interview answer
“Multi-hop retrieval follows dependent evidence steps; agentic RAG adds model-selected search behavior. I bound steps, tools, and cost and preserve provenance.”
Benefits, trade-offs, and production considerations
- Additional hops compound errors and latency.
- Use a deterministic plan when dependencies are known.
- Detect cycles and repeated queries; lack of evidence should lead to abstention, not endless search.
Can you explain it without the notes?
Multi-hop RAG and agentic RAG
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Multi-hop RAG retrieves information in dependent steps: one finding determines the next search. Agentic RAG lets a bounded agent choose retrieval tools or decide whether another search is needed. A fixed two-step retrieval workflow can be multi-hop without…
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Next lesson: Corrective RAG, self-reflective RAG, and context compressionAdapted from 13_AI.MD · “Multi-hop RAG and agentic RAG”. Examples are study fragments; framework behavior can depend on your version.