A2A (Agent-to-Agent) Integration¶

The MCP Gateway supports A2A (Agent-to-Agent) integration, allowing you to register external AI agents and expose them as MCP tools for seamless integration with other agents and MCP clients.

Overview¶

A2A integration enables you to: - Register external AI agents (OpenAI, Anthropic, custom agents) - Expose agents as MCP tools for universal discovery and access - Support multiple protocols (JSONRPC, custom formats) - Manage agent lifecycle through admin UI and APIs - Monitor performance with comprehensive metrics - Configure authentication with various auth methods

Quick Start¶

1. Enable A2A Features¶

# In your .env file or environment variables
MCPGATEWAY_A2A_ENABLED=true
MCPGATEWAY_A2A_METRICS_ENABLED=true

2. Register an A2A Agent¶

Via Admin UI: 1. Go to http://localhost:4444/admin 2. Click the "A2A Agents" tab 3. Fill out the "Add New A2A Agent" form 4. Click "Add A2A Agent"

Via REST API:

curl -X POST "http://localhost:4444/a2a" \
  -H "Authorization: Bearer $MCPGATEWAY_BEARER_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "hello_world_agent",
    "endpoint_url": "http://localhost:9999/",
    "agent_type": "jsonrpc",
    "description": "External AI agent for hello world functionality",
    "auth_type": "api_key",
    "auth_value": "your-api-key",
    "tags": ["ai", "hello-world"]
  }'

3. Test the Agent¶

Via Admin UI: - Click the blue "Test" button next to your agent - See real-time test results

Via API:

curl -X POST "http://localhost:4444/a2a/hello_world_agent/invoke" \
  -H "Authorization: Bearer $MCPGATEWAY_BEARER_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "parameters": {
      "method": "message/send",
      "params": {
        "message": {
          "messageId": "test-123",
          "role": "user",
          "parts": [{"type": "text", "text": "Hello!"}]
        }
      }
    },
    "interaction_type": "test"
  }'

4. Create Virtual Server with A2A Agent¶

curl -X POST "http://localhost:4444/servers" \
  -H "Authorization: Bearer $MCPGATEWAY_BEARER_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "AI Assistant Server",
    "description": "Virtual server with AI agents",
    "associated_a2a_agents": ["agent-id-from-step-2"]
  }'

5. Use Agent via MCP Protocol¶

# A2A agents are now available as MCP tools
curl -X POST "http://localhost:4444/rpc" \
  -H "Authorization: Bearer $MCPGATEWAY_BEARER_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "method": "tools/call",
    "params": {
      "name": "a2a_hello_world_agent",
      "arguments": {
        "method": "message/send",
        "params": {"message": {"messageId": "test", "role": "user", "parts": [{"type": "text", "text": "Hi!"}]}}
      }
    },
    "id": 1
  }'

Agent Types¶

Generic/JSONRPC Agents¶

For agents that expect standard JSONRPC format:

{
  "agent_type": "jsonrpc",
  "endpoint_url": "http://your-agent/",
  "protocol_version": "1.0"
}

OpenAI-compatible Agents¶

{
  "agent_type": "openai",
  "endpoint_url": "https://api.openai.com/v1/chat/completions",
  "auth_type": "api_key",
  "auth_value": "your-openai-api-key"
}

Anthropic-compatible Agents¶

{
  "agent_type": "anthropic",
  "endpoint_url": "https://api.anthropic.com/v1/messages",
  "auth_type": "api_key",
  "auth_value": "your-anthropic-api-key"
}

Custom Agents¶

{
  "agent_type": "custom",
  "endpoint_url": "https://your-custom-agent.com/api",
  "auth_type": "bearer",
  "auth_value": "your-token",
  "capabilities": {"streaming": true, "functions": false},
  "config": {"max_tokens": 1000, "temperature": 0.7}
}

Authentication Methods¶

Protocol Detection¶

The gateway automatically detects agent protocols:

• JSONRPC Format: For agent_type: "jsonrpc" or URLs ending with /
• Custom A2A Format: For other agent types

Monitoring and Metrics¶

A2A agents provide comprehensive metrics: - Execution Count: Total number of invocations - Success Rate: Percentage of successful calls - Response Times: Min/max/average response times - Last Interaction: Timestamp of most recent call - Error Tracking: Failed call details and error messages

Virtual Server Integration¶

Associate A2A agents with virtual servers to: - Organize agents by purpose or team - Control access via server-specific endpoints - Group capabilities for specific use cases - Enable MCP discovery for client tools

Configuration¶

Security Considerations¶

• Encrypted Storage: Agent credentials are encrypted in the database
• Rate Limiting: Configurable limits on agent invocations
• Access Control: Full authentication and authorization
• Audit Logging: All agent interactions are logged
• Network Security: HTTPS support and SSL verification

Troubleshooting¶

Agent Not Responding¶

1. Check agent status in Admin UI (should be "Active" and "Reachable")
2. Verify endpoint URL is correct and accessible
3. Test authentication credentials
4. Check agent logs for protocol format issues

Protocol Format Issues¶

1. Verify agent expects JSONRPC format vs custom format
2. Check required fields in agent's API documentation
3. Use Admin UI test button to validate communication
4. Review gateway logs for request/response details

Authentication Problems¶

1. Verify auth_type matches agent's expected authentication
2. Check auth_value is correct and not expired
3. Test direct agent communication outside gateway
4. Review agent's authentication documentation

For more information on MCP Gateway features and configuration, see the main documentation.