A2A Client MCP Server

An MCP server that acts as a client to the Agent-to-Agent (A2A) protocol, allowing LLMs to interact with A2A agents through the Model Context Protocol (MCP).

Features

• Connect to any A2A-compatible agent

• Send and receive messages

• Track and manage tasks

• Support for streaming responses

• Query agent capabilities and metadata

Installation

# Install globally
npm install -g a2a-client-mcp-server

# Or run directly with npx
npx a2a-client-mcp-server

Configuration

Environment Variables

• A2A_ENDPOINT_URL: URL of the A2A agent to connect to (default: "http://localhost:41241")

Usage with Claude Desktop

Add this to your claude_desktop_config.json:

NPX

npm run build
npm link

{
  "mcpServers": {
    "a2a-client": {
      "command": "npx",
      "args": ["-y", "a2a-client-mcp-server"],
      "env": {
        "A2A_ENDPOINT_URL": "http://localhost:41241"
      }
    }
  }
}

Docker

Build the Docker image:

docker build -t a2a-client-mcp-server .

Configure Claude Desktop:

{
  "mcpServers": {
    "a2a-client": {
      "command": "docker",
      "args": [
        "run",
        "-i",
        "--rm",
        "-e",
        "A2A_ENDPOINT_URL",
        "a2a-client-mcp-server"
      ],
      "env": {
        "A2A_ENDPOINT_URL": "http://localhost:41241"
      }
    }
  }
}

Available Tools

a2a_send_task

Send a task to an A2A agent

• message (string): Message to send to the agent

• taskId (string, optional): Task ID (generated if not provided)

a2a_get_task

Get the current state of a task

• taskId (string): ID of the task to retrieve

a2a_cancel_task

Cancel a running task

• taskId (string): ID of the task to cancel

a2a_send_task_subscribe

Send a task and subscribe to updates (streaming)

• message (string): Message to send to the agent

• taskId (string, optional): Task ID (generated if not provided)

• maxUpdates (number, optional): Maximum updates to receive (default: 10)

a2a_agent_info

Get information about the connected A2A agent

• No parameters required

Resources

The server provides access to two MCP resources:

• a2a://agent-card: Information about the connected A2A agent

• a2a://tasks: List of recent A2A tasks

Example Usage

This example shows how to use A2A Client MCP Server to interact with a Coder Agent:

First, let me explore what A2A agent we're connected to.

I'll use the a2a_agent_info tool to check the agent details.

The agent provides a coding service that can generate files based on natural language instructions. Let's create a simple Python script.

I'll use the a2a_send_task tool to send a request:

Task: "Create a Python function that calculates the Fibonacci sequence"

Now I can check the task status using a2a_get_task with the task ID from the previous response.

The agent has created the requested Python code. I can now retrieve and use this code in my project.

Development

# Install dependencies
npm install

# Build the project
npm run build

# Run in development mode
npm run watch

License

MIT