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# 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](https://github.com/astral-sh/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
```sh
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.
```sh
# Run from the root of the project
uv sync
```
Next, install the Node.js dependencies for the frontend.
```sh
# 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.
```sh
# 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.
```sh
# 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](http://127.0.0.1:5001)**
