A2A Protocol Inspector

The A2A Inspector is a web-based tool designed to help developers inspect, debug, and validate servers that implement the Google A2A (Agent-to-Agent) protocol. It provides a user-friendly interface to interact with an A2A agent, view communication, and ensure specification compliance.

The application is built with a FastAPI backend and a TypeScript frontend.

Features

• Connect to a local A2A Agent: Specify the base URL of any agent server to connect (e.g., http://localhost:5555).
• View Agent Card: Automatically fetches and displays the agent's card.
• Spec Compliance Checks: Performs basic validation on the agent card to ensure it adheres to the A2A specification.
• Live Chat: A chat interface to send and receive messages with the connected agent.
• Debug Console: A slide-out console shows the raw JSON-RPC 2.0 messages sent and received between the inspector and the agent server.

Prerequisites

• Python 3.10+
• uv
• Node.js and npm

Project Structure

This repository is organized into two main parts:

• ./backend/: Contains the Python FastAPI server that handles WebSocket connections and communication with the A2A agent.
• ./frontend/: Contains the TypeScript and CSS source files for the web interface.

Setup and Running the Application

Follow these steps to get the A2A Inspector running on your local machine. The setup is a three-step process: install Python dependencies, install Node.js dependencies, and then run the two processes.

1. Clone the repository

git clone https://github.com/google-a2a/a2a-inspector.git
cd a2a-inspector

2. Install Dependencies

First, install the Python dependencies for the backend from the root directory. uv sync reads the uv.lock file and installs the exact versions of the packages into a virtual environment.

# Run from the root of the project
uv sync

Next, install the Node.js dependencies for the frontend.

# Navigate to the frontend directory
cd frontend

# Install npm packages
npm install

# Go back to the root directory
cd ..

3. Run the Application

The application requires two processes to run concurrently: the frontend build process (in watch mode) and the backend server.

In your first terminal, run the frontend development server. This will build the assets and automatically rebuild them when you make changes.

# Navigate to the frontend directory
cd frontend

# Build the frontend and watch for changes
npm run build -- --watch

In a second terminal, run the backend Python server.

# Navigate to the backend directory
cd backend

# Run the FastAPI server with live reload
uv run app.py

4. Access the Inspector

Once both processes are running, open your web browser and navigate to: http://127.0.0.1:5001