How to Verify Studio Transport Mode

This guide shows you 5 different ways to verify whether Studio is using HTTP or STDIO transport to communicate with your MCP server.

🔍 Method 1: Visual Indicator (Easiest)

Look at the bottom-left sidebar in Studio:

┌──────────────────────┐
│ Transport: HTTP      │  ← Shows current mode
│ Change in Settings   │
└──────────────────────┘

• HTTP = Using HTTP transport (port 3002)
• STDIO = Using standard input/output

🔍 Method 2: Browser Console Logs (Most Detailed)

Open DevTools Console (F12 or Cmd+Option+I):

HTTP Transport Logs:

🔌 Connecting to SSE endpoint: http://localhost:3002/mcp/sse?clientId=...
SSE connection established
MCP Client connected and ready (HTTP transport)
📤 Sending message to server: {method: "tools/list", ...}
📨 Received message from server: {result: {...}}

STDIO Transport Logs:

MCP Client connected and ready (STDIO transport)

🔍 Method 3: Browser Network Tab (Most Reliable)

Open DevTools Network Tab (F12 → Network):

If using HTTP:

You'll see:

1. SSE Connection: GET /mcp/sse?clientId=... (type: eventsource, status: 200)
2. Message Requests: POST /mcp/message (multiple requests as you interact)

Filter by mcp to see only MCP-related requests.

If using STDIO:

You'll see NO requests to /mcp/sse or /mcp/message.

🔍 Method 4: Browser LocalStorage

Open DevTools Console and run:

localStorage.getItem('mcp_transport')

Output:

• "http" → Using HTTP transport ✅
• "stdio" or null → Using STDIO transport

🔍 Method 5: MCP Server Logs

Check your MCP server console output:

If using HTTP:

NitroStack Server started successfully
   📡 Transport: HTTP
   🌐 HTTP Server: http://0.0.0.0:3002
   📋 Endpoints:
      • SSE: http://0.0.0.0:3002/mcp/sse
      • Messages: http://0.0.0.0:3002/mcp/message

You'll also see connection logs:

New SSE connection established for client: client_1234567890_abc123
Received MCP message: {"method":"tools/list",...}

If using STDIO:

NitroStack Server started successfully
   📡 Transport: STDIO
   📋 Listening on: stdin/stdout

📋 Quick Verification Checklist

🔄 How to Switch Transports

Switch to HTTP:

1. Go to Settings page in Studio
2. Select HTTP Transport
3. Enter URL: http://localhost:3002
4. Click Save & Connect
5. Verify using methods above

Switch to STDIO:

1. Go to Settings page in Studio
2. Select STDIO Transport
3. Enter command: node dist/index.js
4. Click Save & Connect
5. Verify using methods above

Recommended Method for Developers

For development and debugging, use Method 2 (Console Logs) + Method 3 (Network Tab) together:

1. Open DevTools Console (F12)
2. Switch to Network tab
3. Filter by mcp
4. Perform an action (e.g., list tools)
5. Check both console logs and network requests

This gives you the most comprehensive view of what's happening.

Troubleshooting

"Transport shows HTTP but no network requests"

Possible causes:

• Studio is caching the old connection
• Refresh the page (Cmd/Ctrl + R)
• Clear browser cache and localStorage

"Transport shows STDIO but console says HTTP"

Possible causes:

• LocalStorage not updated after switching
• Run in console: localStorage.setItem('mcp_transport', 'stdio')
• Refresh the page

"Can't see any logs"

Solution:

• Make sure Console is set to show all levels (not just errors)
• Check that Console isn't filtered

📚 Related Documentation

• Dual Transport Guide
• HTTP Transport Implementation
• STDIO Transport Implementation

Last Updated: October 30, 2025