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    Artificial Intelligence

    From RAG to Agentic AI: How modern LLM stacks actually work (and where MCP fits)

    LLMs alone aren't production intelligence. You need RAG to ground answers in your data, Context Engineering to make outputs policy- and role-aware, Agentic frameworks (e.g., LangGraph) to plan and act, LLMOps (e.g., LangSmith) to evaluate and observe, and MCP to standardize tool/data access across apps. Together, this is how you get reliable, explainable, and scalable GenAI in the enterprise.

    Abhishek Ray
    CEO & Director
    January 15, 2025
    18 min read
    RAG
    LangChain
    LangGraph
    MCP
    Agentic AI
    LLMOps
    LangSmith

    Table of Contents

    Key Takeaways

    • RAG reduces hallucinations by grounding LLM outputs in proprietary data
    • Context Engineering shapes model reasoning with roles, policies, and memory
    • LangGraph enables stateful, multi-step agentic workflows with HITL
    • MCP standardizes tool and data access across AI applications
    • LangSmith provides essential observability and evaluation for production AI
    • LangServe simplifies deployment of AI chains and agents as REST APIs

    🎯 TL;DR

    LLMs alone aren't production intelligence. You need RAG to ground answers in your data, Context Engineering to make outputs policy- and role-aware, Agentic frameworks (e.g., LangGraph) to plan and act, LLMOps (e.g., LangSmith) to evaluate and observe, and MCP to standardize tool/data access across apps. Together, this is how you get reliable, explainable, and scalable GenAI in the enterprise.

    Why this matters now

    RAG is the de-facto way to cut hallucinations by injecting live, proprietary knowledge into prompts.

    Agentic systems turn one-shot prompts into plans with tools, memory, and multi-step control flow.

    MCP (Model Context Protocol) is emerging as the USB-C for AI apps, standardizing how models access tools, data, and prompts.

    LangChain/LangGraph/LangSmith/LangServe give you the bricks for building, orchestrating, testing, and serving—all production-grade.

    The ecosystem at a glance

    QueryRelevant chunks + metadataTool calls
    User / App
    Retriever + Reranker
    Context Engineering Layer
    Agent (LangGraph)
    Tools/APIs via MCP
    Chat Model
    LangSmith Evals + Traces
    LangServe / API

    What each piece does (in one line):

    • RAG: find the right facts; hand them to the model.
    • Context engineering: shape how the model reasons (roles, constraints, memory).
    • Agent (LangGraph): plan multi-step work, manage state, branch/loop, add HITL.
    • MCP: standard interface to tools, data, and prompts across AI apps.
    • LangSmith: trace, evaluate, monitor quality/cost/latency.
    • LangServe: expose chains/agents as secure REST APIs.

    1) Retrieval-Augmented Generation (RAG): ground answers in your truth

    What it is: a pattern that retrieves relevant knowledge (DBs, documents, EHRs, wikis) and injects it into the model's context so outputs cite real data.

    Minimal RAG in code (Python, LangChain style):

    from langchain_openai import ChatOpenAI, OpenAIEmbeddings
    from langchain_core.prompts import ChatPromptTemplate
    from langchain_community.vectorstores import FAISS
    from langchain_text_splitters import RecursiveCharacterTextSplitter
    
    # 1) Ingest & index
    docs = ["<your doc 1 text>", "<your doc 2 text>"]  # replace with loaders
    splits = RecursiveCharacterTextSplitter(chunk_size=800, chunk_overlap=120).split_text("\n\n".join(docs))
    vs = FAISS.from_texts(splits, OpenAIEmbeddings())
    
    # 2) Retrieve
    retriever = vs.as_retriever(search_kwargs={"k": 4})
    
    # 3) Prompt with grounded context
    prompt = ChatPromptTemplate.from_messages([
      ("system", "Answer using the provided context. If unknown, say 'I don't know'. Cite sources."),
      ("human", "Question: {question}\n\nContext:\n{context}")
    ])
    
    def answer(question: str):
        ctx_docs = retriever.get_relevant_documents(question)
        ctx = "\n\n".join([d.page_content for d in ctx_docs])
        return ChatOpenAI(model="gpt-4o", temperature=0).invoke(prompt.format(question=question, context=ctx))
    
    print(answer("What did our Q2 compliance report say about sepsis alerts?"))

    💡 Callout — Why RAG beats fine-tuning for facts

    For "current, specific, and verifiable" knowledge, retrieval is cheaper, faster, and safer than constant re-training. It also reduces hallucinations by grounding answers in retrieved text.

    2) Context Engineering: make models think like your business

    Goal: apply role, policy, structure, and memory so outputs are consistent, compliant, and useful.

    What we layer in practice:

    • Role conditioning: "You are a clinical QA auditor…"
    • Decision constraints: guardrail policies, answer formats, routing rules.
    • Memory: short-term (turn-level) + long-term (task/session history).
    • Data orchestration: "for SQL questions → run tool; for policy → cite doc; else → RAG."

    (This is where Finarb's consulting-led design shows up: we codify process & compliance into the prompt+tooling layer so outputs match how your org reasons.)

    3) Agentic AI with LangGraph: from answers to actions

    LLMs don't just chat; they can plan—call tools, write code, check results, and iterate. LangGraph gives you a stateful graph to do this reliably (persistence, branching, human-in-the-loop, debugging with LangSmith, and prod-ready deployment).

    Tiny agent graph (conceptual Python):

    from langgraph.graph import StateGraph, END
    
    def plan(state):    # decide next step(s)
        # inspect user goal + context → choose "search" or "sql" or "summarize"
        return {"next": "search" if "guidelines" in state["goal"] else "sql"}
    
    def search(state):  # call retriever / web / RAG
        return {"context": "...retrieved passages...", "next": "respond"}
    
    def sql(state):     # call DB tool, return rows
        return {"context": "...query results...", "next": "respond"}
    
    def respond(state): # LLM crafts final answer with citations
        return {"answer": "...final...", "next": END}
    
    g = StateGraph()
    for n in [plan, search, sql, respond]: g.add_node(n.__name__, n)
    g.add_edge("plan", "search"); g.add_edge("plan", "sql")
    g.add_edge("search", "respond"); g.add_edge("sql", "respond")
    agent = g.compile()
    print(agent.invoke({"goal": "Summarize latest clinical guidelines for sepsis"}))

    🎯 Callout — Why LangGraph

    It's a low-level orchestration framework for long-running, stateful agents with durable execution, HITL, and deep LangSmith integration for debugging/evals—used by teams shipping production agents today.

    4) MCP: the missing standard for tools, data, and prompts

    What is MCP? The Model Context Protocol is an open standard so AI apps/agents can plug into data "resources," callable "tools," and reusable "prompts" through a common interface—think USB-C for AI.

    Why you care:

    Stop building bespoke connectors for every app. Integrate once; reuse across assistants.

    Strong security posture: consent, privacy, and tool-safety are first-class in the spec.

    Works with agent frameworks: expose tools/resources via MCP servers; agents (LangGraph, others) consume them.

    MCP in one minute (concept):

    {
      "server": "ehr-mcp",
      "features": {
        "resources": ["ehr://patients/{id}", "ehr://labs/{id}"],
        "tools": ["get_patient_summary", "run_sql", "create_ticket"],
        "prompts": ["clinical_audit_template", "phi_redaction_prompt"]
      }
    }

    Takeaway: MCP lets your data and tools be first-class citizens that any compliant agent can use safely and consistently.

    5) LLMOps you can't skip: LangSmith + LangServe

    LangSmith

    The observability & evaluation layer—trace every run, build datasets from traces, run evals (LLM-as-judge + human), monitor quality/cost/latency. Self-host options exist for strict data boundaries.

    LangServe

    Ship chains/agents as REST APIs (FastAPI/pydantic), with client SDKs. Clean handoff from R&D to prod.

    How it ties together (reference architecture)

    Question / TaskInvoke(state)Retrieve contextChunks + citationsCall tool (SQL/EHR/Search)ResultsFinal answer (+ citations)Trace + metrics + eval hooks
    User/App
    LangServe API
    LangGraph Agent
    RAG (Retriever/Reranker)
    MCP Servers (Tools/Resources)
    LangSmith

    Where this is going (2025+)

    Richer RAG

    Graph-aware retrieval, hybrid sparse+dense, reranking, provenance tracking.

    Agentic maturity

    Long-running agents with robust state, guardrails, and HITL checkpoints (LangGraph direction).

    Standardized tool/data access

    MCP unifying how assistants connect to your systems across vendors.

    Tighter LLMOps loops

    Eval-driven iteration (LangSmith) becomes table stakes for compliance and ROI.

    What Finarb brings

    As a consult-to-operate partner, we don't just wire components—we design the decision system around your business:

    • RAG done right: document governance, chunking/reranking choices, schema-aware SQL tools, and audit-ready citations.
    • Context engineering that encodes roles, policies, and KPIs (esp. for healthcare/BFSI) into prompts + tools.
    • Agentic workflows the way teams actually work—Data Scientist ↔ Programmer ↔ SME agents with HITL gates.
    • LLMOps & security: ISO-aligned, HIPAA-aware deployments; evals and tracing via LangSmith; APIs via LangServe.
    • MCP strategy: define which tools/data become MCP "resources" so your assistants are portable across apps.
    RAG
    LangChain
    LangGraph
    MCP
    Agentic AI
    LLMOps
    LangSmith
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