A2A Hello World

Project Overview

This project serves as a foundational "Hello World" example for developing agents using the Google Agent Development Kit (ADK) and the Agent-to-Agent (A2A) protocol. It demonstrates how to build a simple Python-based agent capable of interacting with external tools (like fetching weather and time information) and provides a comprehensive set of scripts for local development, testing, and deployment to Google Cloud Run. The primary goal is to offer a clear, runnable template for developers to quickly get started with ADK and A2A agent development, showcasing the power of inter-agent communication.

Setup Scripts

• init.sh: Initializes the environment by prompting the user for their Google Cloud project ID and Gemini API Key. It also runs gcloud auth application-default login to get user credentials.
• set_env.sh: Sets various environment variables required for the other scripts to run. It reads the project ID and Gemini key from the files created by init.sh. This script also sets the PUBLIC_URL environment variable, which is used to configure the public URL for the agent.

ADK Execution Scripts

These scripts facilitate running the agent in various modes and environments:

• cli.sh / run.sh: Runs the agent in command-line mode, allowing you to interact with it from your terminal. run.sh is an alias for cli.sh.
• local.sh: Runs the agent in a local web server, accessible typically at http://localhost:8080.
• web.sh: Runs the agent in a local web server and automatically opens the UI in your default web browser.
• api_server.sh: Runs the agent in API server mode, exposing its functionalities via a RESTful API.
• cloudrun.sh: Deploys the agent as a scalable service to Google Cloud Run, making it accessible publicly.

Agent-Specific Execution Scripts

These scripts are tailored for specific agents within the project, demonstrating various A2A interactions and functionalities:

• a2acard.sh: Runs the a2a-agentcard agent, which handles agent card-related interactions.
• a2aevents.sh: Executes the a2a-events agent, designed for finding events with Google Search Tool.
• a2ahello.sh: Runs the a2a-hello-world agent, a basic example of A2A communication.
• a2amaster.sh: Starts the a2a-master-agent, which orchestrates interactions between other agents.
• a2atest.sh: A utility script for testing A2A agent functionalities.
• a2aweather.sh: Runs the a2a-weather-time agent, demonstrating tool usage for weather and time information.

Agent Details

The core agent logic is defined in src/agents/a2a_hello_world/agent.py. This simple agent demonstrates:

• Tool Usage: It utilizes two predefined tools: get_weather to retrieve current weather conditions for a specified city, and get_current_time to obtain the current time for a given location.
• Model Integration: The agent is configured to use the gemini-2.5-flash model for its conversational capabilities and tool orchestration.
• Direct Execution: The agent.py script can be run directly to start a uvicorn server, which is useful for local development and testing.

A2A Protocol Integration

This project highlights the integration of the Agent-to-Agent (A2A) protocol, enabling seamless communication between different agents. The agent-specific scripts (e.g., a2ahello.sh, a2aweather.sh) are designed to run agents in A2A mode, allowing them to send and receive messages from other agents. This setup is crucial for building complex multi-agent systems where specialized agents collaborate to achieve a larger goal. The a2a-hello-world agent, while simple, provides a clear example of how to expose an agent's capabilities for inter-agent communication using the ADK framework.

Development

To extend or modify this agent:

1. Locate Agent Code: The main agent implementation is in src/agents/a2a_hello_world/agent.py.
2. Add Tools: Define new tools within the agent's tools list, similar to get_weather and get_current_time.
3. Modify Agent Logic: Adjust the agent's prompt or add new functionalities within the agent.py file.
4. Dependencies: If new Python packages are required, add them to src/agents/a2a_hello_world/requirements.txt. For development dependencies, add them to the root requirements.txt.
5. Testing: Utilize the cli.sh or local.sh scripts for quick local testing during development.

a2a-benchmark