A2A + mcp-use: Complete MCP Integration

A2A is a MCP server that An MCP server that bridges the Model Context Protocol (MCP) with the Agent-to-Agent (A2A) protocol, enabling MCP-compatible AI assistants (like Claude) to seamlessly interact with A2A agents..

When integrated with mcp-use, you can:

• Register and manage A2A agents for communication
• Send messages to A2A agents and handle responses
• Manage asynchronous tasks and retrieve results

This guide provides step-by-step instructions to set up A2A in mcp-use, including configuration, examples, and troubleshooting.

What You'll Achieve

After completing this setup:

• A2A will be fully integrated and operational
• You can use A2A tools directly in mcp-use
• All A2A capabilities will be available for your workflows
• Access to 4 different tools

Prerequisites

Before starting, ensure you have:

• mcp-use installed and configured
• Compatible operating system (Python 3.8+, Node.js 16+, pip Installation, npm/yarn Installation)

Installation

Step 1: Install A2A

Configuration

Step 2: Configure mcp-use

1. Open mcp-use settings
2. Navigate to MCP server configuration
3. Add A2A server with appropriate settings
4. Save and restart if needed

Examples

Once configured, you can use A2A in mcp-use:

Register and Communicate with Agent

Set up communication with an A2A agent

Ask mcp-use: "Register an agent for data analysis tasks and send it a dataset processing request"

Expected Result: Agent registered, task submitted, and task_id returned for tracking

Stream Real-Time Data

Use streaming to get real-time updates from agent

Ask mcp-use: "Stream live updates from the monitoring agent about system metrics"

Expected Result: Continuous stream of system metrics and status updates

Manage Multiple Agents

Coordinate tasks across multiple A2A agents

Ask mcp-use: "List all available agents and distribute parallel processing tasks"

Expected Result: Agent list displayed, tasks distributed, and progress tracked

Handle Task Results

Retrieve and process completed task results

Ask mcp-use: "Get the results from the data analysis task I submitted earlier"

Expected Result: Task results retrieved with processed data and analysis findings

Testing Your Setup

1. Launch mcp-use
2. Verify A2A is available in the tools list
3. Test basic A2A functionality

Troubleshooting

Common Issues

Agent Registration Failed

Symptoms: Registration errors, Agent not found, Connection timeouts

Cause: Network connectivity issues or invalid agent configuration

Solution:

• Check internet connectivity to A2A network
• Verify agent endpoint URLs are correct
• Ensure agent is online and accepting connections
• Check firewall settings and port accessibility

Task Never Completes

Symptoms: Task stuck in pending state, No response from agent

Cause: Agent overload, network issues, or task complexity

Solution:

• Check agent status and availability
• Cancel and resubmit the task
• Break complex tasks into smaller parts
• Try different agent if available

Transport Protocol Errors

Symptoms: Connection refused, Protocol mismatch errors

Cause: Incorrect transport configuration or port conflicts

Solution:

• Verify MCP_TRANSPORT setting matches client expectations
• Check MCP_HOST and MCP_PORT are accessible
• Ensure no port conflicts with other services
• Try different transport mode (stdio, http, sse)

Message Streaming Issues

Symptoms: Broken streams, Incomplete messages, Timeout errors

Cause: Network instability or buffer overflow

Solution:

• Check network stability and bandwidth
• Reduce message frequency or size
• Enable debug logging to trace issues
• Use appropriate buffer sizes for streaming

Connection Refused or Server Unreachable

Symptoms: ECONNREFUSED error, Connection timeout, Cannot reach server

Cause: MCP server not running or incorrect URL

Solution:

• Verify MCP server is running and accessible
• Check server URL is correct (protocol, host, port, path)
• Test server URL in browser or with curl to confirm it responds
• Ensure firewall allows connections to server port
• Verify CORS settings if accessing from browser

Import Errors or Module Not Found

Symptoms: ModuleNotFoundError: mcp_use, Cannot find module "mcp-use"

Cause: Package not installed or wrong environment

Solution:

• Verify installation: pip show mcp-use (Python) or npm list mcp-use (JS)
• Ensure using correct Python virtual environment or Node.js project
• Reinstall package: pip install --upgrade mcp-use or npm install mcp-use
• Check package.json or requirements.txt includes mcp-use

Tool Discovery Returns Empty List

Symptoms: list_tools() returns [], No tools available, Tools not found

Cause: MCP server not properly configured or not exposing tools

Solution:

• Verify MCP server is properly initialized and configured
• Check server logs to confirm tools are registered
• Test server directly with MCP inspector or test client
• Ensure server implements MCP protocol correctly
• Verify transport type (HTTP/SSE) matches server configuration

Tool Execution Fails or Returns Errors

Symptoms: Tool call throws exception, Invalid arguments error, Execution timeout

Cause: Incorrect arguments or server-side execution failure

Solution:

• Verify tool arguments match schema definition from list_tools()
• Check required arguments are provided with correct types
• Review server logs for detailed error messages
• Test tool with minimal valid arguments first
• Increase timeout if tool requires longer execution time

LangChain.js Integration Not Working

Symptoms: getLangChainTools() fails, Tools not recognized by agent, Type errors

Cause: Version mismatch or incorrect integration setup

Solution:

• Ensure LangChain.js version is compatible with mcp-use
• Verify TypeScript version meets requirements
• Check tool schema conversion is working correctly
• Use latest versions of both mcp-use and LangChain.js
• Review LangChain.js documentation for agent setup

Transport Type Errors (HTTP vs SSE)

Symptoms: SSE connection fails, HTTP polling not working, Event stream errors

Cause: Mismatch between client transport and server capabilities

Solution:

• Verify server supports the transport type you are using
• Try alternative transport: switch between "http" and "sse"
• Check server documentation for supported transport types
• For SSE, ensure server sends proper Content-Type: text/event-stream
• For HTTP, verify server accepts POST requests with JSON payload

A2A not appearing in mcp-use

Symptoms: Server not listed, Tools not available

Cause: Configuration or installation issue

Solution:

• Verify configuration syntax
• Check A2A installation
• Restart mcp-use
• Check logs for error messages

Next Steps

Now that A2A is integrated with mcp-use:

• Explore all A2A capabilities through mcp-use
• Check out other MCP servers that work with mcp-use
• Join the MCP community for tips and support
• Consider contributing to A2A development

Need Help?

• Search for A2A documentation
• Check the mcp-use MCP guide
• Join the MCP community discussions