Connect Your Client

Add the MCP Client Tester server to your LLM client in minutes. This public server helps you test and debug MCP protocol implementations.

Public Server Endpoint

https://api.mcp-tester.l.supported.systems/mcp

This endpoint supports Streamable HTTP transport (JSON-RPC over HTTPS).

Tip

The MCP Client Tester server provides tools for testing protocol features like ping, echo, progress notifications, cancellation, and error handling.

Quick Setup by Client

Claude.ai (Web)

Claude.ai Web Client Setup

Claude.ai (the web interface at claude.ai) supports MCP integrations for Pro, Team, and Enterprise users.

Note

MCP support in Claude.ai requires a paid subscription (Pro, Team, or Enterprise).

Setup Steps:

1. Go to claude.ai and sign in
2. Click your profile icon → Settings
3. Navigate to Integrations or MCP Servers
4. Click Add Integration or Add MCP Server
5. Enter:
   • Name: MCP Client Tester
   • URL: https://api.mcp-tester.l.supported.systems/mcp
6. Click Save or Connect

Once connected, you can ask Claude to use the MCP tools:

Use the ping tool from MCP Client Tester with message "hello"

Claude Code

Claude Code Setup

Add the MCP server using the CLI:

claude mcp add mcp-tester --transport http https://api.mcp-tester.l.supported.systems/mcp

Or add it manually to your Claude Code settings:

Via Settings UI:

1. Open Claude Code settings
2. Navigate to MCP Servers
3. Click Add Server
4. Enter:
   • Name: mcp-tester
   • Transport: http
   • URL: https://api.mcp-tester.l.supported.systems/mcp

Via config file (~/.claude/settings.json):

{
  "mcpServers": {
    "mcp-tester": {
      "transport": "http",
      "url": "https://api.mcp-tester.l.supported.systems/mcp"
    }
  }
}

Claude Desktop

Claude Desktop Setup

Claude Desktop primarily uses STDIO transport. For HTTP-based servers, you’ll need a bridge or use experimental HTTP support (v1.3+).

Option 1: Using mcp-remote (Recommended)

Install the mcp-remote bridge:

npm install -g @anthropic/mcp-remote

Add to your claude_desktop_config.json:

{
  "mcpServers": {
    "mcp-tester": {
      "command": "mcp-remote",
      "args": [
        "--transport", "http",
        "--url", "https://api.mcp-tester.l.supported.systems/mcp"
      ]
    }
  }
}

Option 2: Direct HTTP (v1.3+ experimental)

{
  "mcpServers": {
    "mcp-tester": {
      "transport": "http",
      "url": "https://api.mcp-tester.l.supported.systems/mcp"
    }
  }
}

Caution

Direct HTTP transport in Claude Desktop is experimental and may not work in all versions.

Python SDK

Python MCP SDK

from mcp import Client
from mcp.transports.http import HTTPClientTransport

async def connect_to_tester():
    transport = HTTPClientTransport(
        url="https://api.mcp-tester.l.supported.systems/mcp"
    )

    async with Client(transport) as client:
        # Initialize connection
        await client.initialize()

        # List available tools
        tools = await client.list_tools()
        print(f"Available tools: {[t.name for t in tools]}")

        # Call the ping tool
        result = await client.call_tool("ping", {"message": "hello"})
        print(f"Ping response: {result}")

TypeScript SDK

TypeScript MCP SDK

import { Client } from '@modelcontextprotocol/sdk/client';
import { HTTPClientTransport } from '@modelcontextprotocol/sdk/client/http';

const transport = new HTTPClientTransport({
  url: 'https://api.mcp-tester.l.supported.systems/mcp'
});

const client = new Client(transport);

await client.connect();

// List available tools
const tools = await client.listTools();
console.log('Available tools:', tools.map(t => t.name));

// Call the ping tool
const result = await client.callTool('ping', { message: 'hello' });
console.log('Ping response:', result);

cURL / HTTP

Direct HTTP Requests

Test the MCP endpoint directly with cURL:

Initialize Connection:

curl -X POST https://api.mcp-tester.l.supported.systems/mcp \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "id": 1,
    "method": "initialize",
    "params": {
      "protocolVersion": "2024-11-05",
      "capabilities": {},
      "clientInfo": {
        "name": "my-test-client",
        "version": "1.0.0"
      }
    }
  }'

List Tools:

curl -X POST https://api.mcp-tester.l.supported.systems/mcp \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "id": 2,
    "method": "tools/list",
    "params": {}
  }'

Call a Tool:

curl -X POST https://api.mcp-tester.l.supported.systems/mcp \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "id": 3,
    "method": "tools/call",
    "params": {
      "name": "ping",
      "arguments": {"message": "hello from curl"}
    }
  }'

Available Tools

Once connected, you’ll have access to these testing tools:

Tool	Description
ping	Basic connectivity test - returns pong with timestamp
echo	Echo back any input you send
tell_us_about_yourself	Client self-reporting for capability testing
test_progress	Test progress notification handling
test_cancellation	Test operation cancellation support
test_error	Test error handling with various error types
get_server_capabilities	Discover server features and configuration

Testing Your Connection

After adding the server, verify the connection works:

1. Check Server Status

   Use the ping tool to verify connectivity:

   Use the ping tool with message "hello"

2. Explore Available Tools

   Ask your client to list available tools or use get_server_capabilities

3. Test Protocol Features

   Try test_progress to see how your client handles progress notifications

4. Test Error Handling

   Use test_error with different error types to verify error handling

Troubleshooting

Connection Issues

“Connection refused” or timeout:

• Verify the URL is correct: https://api.mcp-tester.l.supported.systems/mcp
• Check your network allows HTTPS connections
• Try the cURL test above to isolate client vs. network issues

“Transport not supported”:

• Ensure your client supports HTTP/HTTPS transport
• Some clients (older Claude Desktop) only support STDIO
• Use mcp-remote bridge for STDIO-only clients

JSON-RPC errors:

• Check that your client sends proper JSON-RPC 2.0 format
• Ensure Content-Type header is application/json
• Verify the method name and parameters match the schema

Getting Help

• View Logs: Check the Monitor page for real-time protocol logs
• API Docs: Visit https://api.mcp-tester.l.supported.systems/docs for OpenAPI documentation
• Dashboard: Use the Dashboard to see session statistics

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Ready to dive deeper? Check out the Protocol Overview to understand the MCP message format, or explore Testing Strategies for comprehensive testing.