Agent-to-Agent (A2A) orchestration is where multiple autonomous agents collaborate by passing tasks, context, or results to one another. Instead of one monolithic agent, you compose a workflow of specialized agents. This is very relevant to LangGraph (or LangChain agents) where you model workflows as graphs.

Let me walk you through step-by-step with sample code.


🔹 Conceptual Flow

  1. ResearchAgent

    • Takes a query.
    • Fetches/searches data (stubbed in example).
    • Produces structured output.
  2. SummarizerAgent

    • Takes research output.
    • Summarizes into digestible text.
  3. ReviewerAgent

    • Checks the summary for clarity, correctness.
    • Adds final polish.
  4. Orchestrator (LangGraph / simple Python driver)

    • Connects these agents in sequence.
    • Ensures one agent’s output feeds the next.

🔹 Minimal Python Example (LangGraph)

from langchain_openai import ChatOpenAI
from langgraph.graph import StateGraph, END

# --- Define Agents ---
llm = ChatOpenAI(model="gpt-4o-mini")

def research_agent(state):
    query = state["query"]
    return {
        "research": f"Stub: Collected 3 facts about '{query}'."
    }

def summarizer_agent(state):
    research = state["research"]
    response = llm.invoke(f"Summarize this research: {research}")
    return {"summary": response.content}

def reviewer_agent(state):
    summary = state["summary"]
    response = llm.invoke(f"Review and polish this summary: {summary}")
    return {"final": response.content}

# --- Build Orchestration Graph ---
workflow = StateGraph(dict)

workflow.add_node("research", research_agent)
workflow.add_node("summarizer", summarizer_agent)
workflow.add_node("reviewer", reviewer_agent)

workflow.set_entry_point("research")
workflow.add_edge("research", "summarizer")
workflow.add_edge("summarizer", "reviewer")
workflow.add_edge("reviewer", END)

graph = workflow.compile()

# --- Run Example ---
result = graph.invoke({"query": "Quantum computing in education"})
print(result["final"])

🔹 How Orchestration Happens (Step-by-Step)

  • State Management: Each agent updates the shared state dict. This makes hand-off explicit. (LangGraph automatically manages this shared state).

  • Directed Graph: workflow.add_edge("A", "B") defines A→B flow. Agents only need to know their inputs/outputs, not each other.

  • LLM + Function Nodes: Some nodes use LLM calls (ChatOpenAI), others can be deterministic code (research_agent).


🔹 Why This Is A2A Orchestration

  • Autonomy: Each agent is independent, doesn’t know who comes next.
  • Orchestration: The graph coordinates their execution.
  • Composable: Swap out SummarizerAgent for another summarizer without touching orchestration logic.