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The system features two specialized agents: a Bear Agent (risk-focused) built with Pydantic AI, and a Bull Agent (opportunity-focused) built with Google ADK. Both agents communicate using the A2A protocol and are enhanced with custom tools through MCP. The purpose of this tutorial is to highlight A2A observability and associated opentelemetry traces in Arize and Phoenix platforms. Agent-to-Agent (A2A) Protocol is an open standard for AI agents to communicate and collaborate. Its purpose is to enable interoperability between various AI agents, regardless of their underlying framework or vendor, allowing them to share tasks, data, and partial results. For more information on A2A, see links below:

A2A Documentation

A2A Overview Video

 There are 2 notebook examples provided that send opentelemetry traces to either Phoenix or Arize AX endpoints:
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Colab - Phoenix Tracing
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Colab - Arize Tracing

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Architecture Overview

The multi-agent system consists of three main components:
  • Bear Agent (Pydantic AI + MCP): Focuses on risk analysis, identifying downside catalysts and warning signals
  • Bull Agent (ADK + MCP): Focuses on growth opportunities, bullish patterns, and upside potential
  • Orchestrator Agent (ADK): Coordinates both agents to provide balanced market analysis
The agents communicate using the A2A protocol, which enables standardized agent-to-agent communication with capabilities for:
  • Agent discovery through agent cards
  • Asynchronous task execution
  • Structured message passing
  • Transport protocol negotiation
Observability is provided through Arize tracing, allowing you to monitor agent behavior, tool usage, and performance.

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Prerequisites

  • Before starting this tutorial, ensure you have:
  • Arize Phoenix Cloud or Arize AX account
  • A Google Cloud project with Vertex AI API enabled
  • Appropriate permissions to deploy agents to Vertex AI Agent Engine