Protocol Compatibility: Bridging MCP and A2A

ArtCafe Team
April 15, 2025
11 min read min read
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Bridging MCP and A2A

The AI agent ecosystem is fragmented. Google's Agent-to-Agent (A2A) protocol and Anthropic's Model Context Protocol (MCP) represent different philosophies for agent communication. Here's how ArtCafe.ai provides seamless interoperability between these protocols and more.

The Protocol Problem

Different organizations have created their own agent communication standards:

  • MCP (Model Context Protocol): Anthropic's approach for context sharing
  • A2A (Agent-to-Agent): Google's direct communication protocol
  • OpenAI Assistants API: Function calling and tool use
  • LangChain Hub: Chain-based agent orchestration
  • AutoGPT Protocol: Autonomous agent communication

Each has its strengths, but they don't talk to each other.

Universal Translation Layer

ArtCafe.ai acts as a universal translator between protocols:

// MCP agent publishes
mcp_agent.publish_context({
  "type": "context_update",
  "data": {
    "user_intent": "analyze document",
    "document_id": "doc_123",
    "metadata": {...}
  }
});

// Automatically translated for A2A agents
// A2A agent receives:
{
  "from": "mcp_agent_01",
  "to": "a2a_agent_02",
  "message_type": "task_request",
  "payload": {
    "task": "analyze_document",
    "parameters": {
      "document_id": "doc_123",
      "context": {...}
    }
  }
}

Protocol Adapters

MCP Adapter

class MCPAdapter:
    def __init__(self, artcafe_client):
        self.client = artcafe_client
        
    def send_context(self, context):
        # Convert MCP context to ArtCafe message
        message = {
            "type": "mcp.context",
            "data": context,
            "protocol": "mcp",
            "version": "1.0"
        }
        self.client.publish("protocols.mcp", message)
    
    def receive_context(self, callback):
        # Subscribe to MCP-compatible messages
        self.client.subscribe("protocols.mcp.>", callback)

A2A Adapter

class A2AAdapter:
    def __init__(self, artcafe_client):
        self.client = artcafe_client
        
    def send_message(self, to_agent, message):
        # Convert A2A message to ArtCafe format
        artcafe_msg = {
            "type": "a2a.message",
            "to": to_agent,
            "payload": message,
            "protocol": "a2a",
            "version": "1.0"
        }
        self.client.publish(f"agents.{to_agent}", artcafe_msg)
    
    def register_handler(self, message_type, handler):
        # Handle A2A-style messages
        def wrapper(msg):
            if msg.get("protocol") == "a2a":
                handler(msg["payload"])
        
        self.client.subscribe(f"agents.{self.agent_id}", wrapper)

Semantic Translation

Beyond format conversion, we translate semantics:

class SemanticTranslator:
    def translate_mcp_to_a2a(self, mcp_msg):
        """Convert MCP concepts to A2A equivalents"""
        
        # MCP context updates → A2A state messages
        if mcp_msg["type"] == "context_update":
            return {
                "message_type": "state_change",
                "state": mcp_msg["data"]
            }
        
        # MCP tool calls → A2A function requests
        elif mcp_msg["type"] == "tool_call":
            return {
                "message_type": "function_request",
                "function": mcp_msg["tool"],
                "arguments": mcp_msg["parameters"]
            }
    
    def translate_a2a_to_mcp(self, a2a_msg):
        """Convert A2A concepts to MCP equivalents"""
        
        # A2A task requests → MCP context
        if a2a_msg["message_type"] == "task_request":
            return {
                "type": "context_update",
                "data": {
                    "task": a2a_msg["task"],
                    "parameters": a2a_msg["parameters"]
                }
            }

Cross-Protocol Workflows

Enable agents using different protocols to work together:

# Workflow mixing MCP and A2A agents
workflow = CrossProtocolWorkflow()

# MCP agent provides context
workflow.add_step(
    MCPAgent("context_provider"),
    output="enriched_context"
)

# A2A agent processes data
workflow.add_step(
    A2AAgent("data_processor"),
    input="enriched_context",
    output="processed_data"
)

# OpenAI Assistant generates response
workflow.add_step(
    OpenAIAssistant("responder"),
    input="processed_data",
    output="final_response"
)

# Execute seamlessly
result = await workflow.run(initial_data)

Protocol Features Mapping

Context Handling

# MCP's context windows
mcp_context = {
    "conversation_history": [...],
    "relevant_documents": [...],
    "user_preferences": {...}
}

# Mapped to A2A's state management
a2a_state = {
    "agent_memory": {
        "short_term": conversation_history,
        "long_term": relevant_documents
    },
    "configuration": user_preferences
}

Tool/Function Calling

# OpenAI function calling
openai_function = {
    "name": "get_weather",
    "parameters": {
        "location": "San Francisco"
    }
}

# Translated to MCP tool use
mcp_tool = {
    "tool": "weather_service",
    "action": "get_current",
    "context": {
        "location": "San Francisco"
    }
}

# And A2A service request
a2a_request = {
    "service": "weather",
    "method": "getCurrentWeather",
    "args": ["San Francisco"]
}

Protocol Negotiation

Agents automatically negotiate the best protocol:

class ProtocolNegotiator:
    def negotiate(self, agent_capabilities):
        # Find common protocols
        common = set(self.protocols) & set(agent_capabilities)
        
        if not common:
            # Use ArtCafe as bridge
            return "artcafe_bridge"
        
        # Prefer native protocol if available
        priority = ["mcp", "a2a", "openai", "langchain"]
        for protocol in priority:
            if protocol in common:
                return protocol

Real-World Integration Example

# Company has existing MCP agents
mcp_nlp = MCPAgent("nlp_analyzer")
mcp_knowledge = MCPAgent("knowledge_base")

# Partner uses A2A agents
a2a_validator = A2AAgent("data_validator")
a2a_enricher = A2AAgent("data_enricher")

# New team uses OpenAI
openai_gen = OpenAIAssistant("content_generator")

# All work together seamlessly
pipeline = ArtCafePipeline()
pipeline.connect([
    mcp_nlp,
    a2a_validator,
    mcp_knowledge,
    a2a_enricher,
    openai_gen
])

# Process data through mixed protocols
result = await pipeline.process(user_request)

Performance Considerations

Protocol translation overhead is minimal:

  • Translation latency: <1ms
  • Message overhead: ~5% for metadata
  • Semantic mapping: Cached after first use
  • Direct routing: When same protocol detected

Future-Proof Design

As new protocols emerge, adding support is simple:

# Add new protocol adapter
class NewProtocolAdapter(ProtocolAdapter):
    def translate_to_artcafe(self, message):
        # Define translation logic
        pass
    
    def translate_from_artcafe(self, message):
        # Define reverse translation
        pass

# Register with system
protocol_registry.register("new_protocol", NewProtocolAdapter)

The Best of All Worlds

With ArtCafe.ai, you don't have to choose:

  • Use MCP for context management
  • Use A2A for direct agent communication
  • Use OpenAI for advanced reasoning
  • Use LangChain for complex workflows

They all work together, automatically translated and routed through our universal message bus. Build with the tools you know, integrate with everything else.