Agent-to-Agent Communication

Overview

Hexr implements Google’s Agent-to-Agent (A2A) protocol with SPIFFE identity extensions, enabling agents to:

Discover other agents via Agent Cards
Delegate tasks to specialized agents
Fan out work to multiple agents in parallel
Pipeline sequential processing across agents

Enable A2A

Add a2a=True to your agent decorator:

from hexr import hexr_agent
from hexr.a2a import A2AClient

@hexr_agent(name="coordinator", tenant="acme-corp", a2a=True)
def main():
    a2a = A2AClient()
    
    # Discover agents in the same namespace
    agents = a2a.discover()
    for agent in agents:
        print(f"Found: {agent.name} - {agent.description}")
    
    # Send a task to another agent
    task = a2a.send(
        agent="research-analyst",
        message="Research the latest AI agent frameworks",
    )
    
    # Get the result
    result = a2a.get_task(task.id)
    print(result.output)

Fan-Out Pattern

Send tasks to multiple agents in parallel:

@hexr_agent(name="coordinator", tenant="acme-corp", a2a=True)
def main():
    a2a = A2AClient()
    
    topics = ["quantum computing", "robotics", "biotech"]
    tasks = []
    
    for topic in topics:
        task = a2a.send(
            agent="research-analyst",
            message=f"Research {topic} trends for 2026",
        )
        tasks.append(task)
    
    # Collect results
    results = [a2a.get_task(t.id) for t in tasks]
    
    # Synthesize
    from hexr import hexr_llm
    synthesis = hexr_llm(
        provider="openai",
        model="gpt-4o",
        prompt=f"Synthesize these research results: {results}",
    )
    print(synthesis)

Pipeline Pattern

Chain agents sequentially:

@hexr_agent(name="pipeline-coordinator", tenant="acme-corp", a2a=True)
def main():
    a2a = A2AClient()
    
    # Step 1: Research
    research = a2a.send(agent="researcher", message="AI agent trends 2026")
    research_result = a2a.get_task(research.id)
    
    # Step 2: Write (using research output)
    article = a2a.send(
        agent="writer",
        message=f"Write a blog post about: {research_result.output}",
    )
    article_result = a2a.get_task(article.id)
    
    # Step 3: Edit  
    edited = a2a.send(
        agent="editor",
        message=f"Edit this article: {article_result.output}",
    )
    final = a2a.get_task(edited.id)
    print(final.output)

Security

All A2A communication is:

mTLS encrypted — using SPIFFE SVIDs
Identity verified — each agent’s SPIFFE ID is validated
OPA authorized — policies control which agents can communicate
Audited — every message is traced via OpenTelemetry

Agent A sends task via mTLS

Agent A (coordinator) sends a task to Agent B (researcher) through the Envoy proxy, authenticated with its SPIFFE identity.

OPA authorizes the request

Envoy checks with OPA: “Can coordinator communicate with researcher?” OPA returns ALLOW.

Task delivered over mTLS

Envoy delivers the task to Agent B over mTLS. Agent B processes it and returns the result.

Agent A (coordinator) → Envoy (mTLS) → OPA (authorize) → Agent B (researcher) → Result → A

​Overview

​Enable A2A

​Fan-Out Pattern

​Pipeline Pattern

​Security

Overview

Enable A2A

Fan-Out Pattern

Pipeline Pattern

Security