Connecting to Your MCP Server on Hugging Face Spaces

This guide explains how to connect to your Gradio MCP server deployed on Hugging Face Spaces, based on real-world testing and troubleshooting.

⚠️ Important: This guide reflects actual testing results and working solutions, not just theoretical approaches.

1. Find Your MCP Endpoint

After deploying your Gradio app to Hugging Face Spaces, your MCP endpoint will be:

https://YOUR_USERNAME-YOUR_SPACE_NAME.hf.space/gradio_api/mcp/sse

Example:
If your username is freemansel and your space is mcp-sentiment, your endpoint is:

https://freemansel-mcp-sentiment.hf.space/gradio_api/mcp/sse

Testing the endpoint: You can verify the SSE stream is working by visiting the URL in a browser - you should see periodic ping messages every 15 seconds.

2. ✅ Working Solutions (Tested & Verified)

A. smolagents MCPClient ⭐ RECOMMENDED

Performance: ~0.11 seconds per request (fastest!)
Status: ✅ Works perfectly
Protocol: Native MCP via smolagents

Based on the Hugging Face MCP Course, this is the proper way to use MCP.

Installation

pdm add "smolagents[mcp]"
# or
pip install "smolagents[mcp]"

Python Code

#!/usr/bin/env python3
"""
Working MCP client using smolagents.
Performance: ~0.11 seconds per request
"""

import time
from smolagents.mcp_client import MCPClient

def analyze_sentiment_mcp(text):
    """Analyze sentiment using MCP protocol."""
    mcp_client = None
    try:
        mcp_client = MCPClient(
            {"url": "https://freemansel-mcp-sentiment.hf.space/gradio_api/mcp/sse"}
        )
        
        tools = mcp_client.get_tools()
        sentiment_tool = tools[0]  # The sentiment analysis tool
        
        result = sentiment_tool(text=text)
        return result
        
    finally:
        if mcp_client:
            mcp_client.disconnect()

# Example usage
result = analyze_sentiment_mcp("I love this product!")
print(f"Polarity: {result['polarity']}")
print(f"Assessment: {result['assessment']}")
# Output: Polarity: 0.69, Assessment: positive

Why this works: smolagents handles all the MCP protocol complexity automatically, including the SSE connection and handshake.

B. Gradio Client 🔄 BACKUP SOLUTION

Performance: ~1.3 seconds per request
Status: ✅ Very reliable backup
Protocol: Direct Gradio API access

This bypasses MCP entirely and connects directly to the Gradio API.

Installation

pdm add gradio_client
# or  
pip install gradio_client

Python Code

#!/usr/bin/env python3
"""
Backup solution using Gradio client.
Performance: ~1.3 seconds per request
"""

import time
from gradio_client import Client

def analyze_sentiment_gradio(text):
    """Analyze sentiment using Gradio client."""
    client = Client("https://freemansel-mcp-sentiment.hf.space")
    result = client.predict(text, api_name="/predict")
    return result

# Example usage
result = analyze_sentiment_gradio("I love this product!")
print(f"Polarity: {result['polarity']}")
print(f"Assessment: {result['assessment']}")
# Output: Polarity: 0.69, Assessment: positive

Why this works: Direct API access to Gradio's built-in endpoints, no MCP protocol involved.

3. ❌ Known Issues & Failed Approaches

A. Low-Level MCP Clients (Don't Use)

❌ Problem: The following approach causes session.initialize() to hang indefinitely:

# ❌ THIS HANGS - DON'T USE
import asyncio
from mcp import ClientSession, StdioServerParameters
from mcp.client.stdio import stdio_client

async def broken_mcp_approach():
    server_params = StdioServerParameters(
        command="npx",
        args=["mcp-remote", "https://freemansel-mcp-sentiment.hf.space/gradio_api/mcp/sse"]
    )
    
    async with stdio_client(server_params) as (read, write):
        async with ClientSession(read, write) as session:
            # ❌ This line hangs forever (tested timeout: 45+ seconds)
            await session.initialize()

Root Cause:

The low-level MCP client requires manual protocol handling
session.initialize() times out during MCP handshake
Even though mcp-remote connects successfully, the protocol negotiation fails

Evidence:

STDIO client connects instantly (0.0s)
Session creation works fine
Failure occurs specifically in session.initialize()
Error: "unhandled errors in a TaskGroup (1 sub-exception)"

B. Direct HTTP Requests (Don't Work)

❌ Problem: MCP endpoints don't accept standard HTTP POST requests:

# ❌ THIS FAILS - DON'T USE
import requests

url = "https://freemansel-mcp-sentiment.hf.space/gradio_api/call/sentiment_analysis"
payload = {"data": ["I love this product!"]}
response = requests.post(url, json=payload)
# Result: 500 Internal Server Error or 405 Method Not Allowed

Why it fails:

MCP servers use Server-Sent Events (SSE) protocol
Standard REST API endpoints are not exposed when mcp_server=True
The /gradio_api/mcp/sse endpoint only accepts SSE connections

C. mcp-remote with Manual Clients (Problematic)

⚠️ Partial Success: mcp-remote proxy connects but has protocol issues:

# This establishes SSE connection but MCP protocol still fails
npx mcp-remote https://freemansel-mcp-sentiment.hf.space/gradio_api/mcp/sse

What happens:

✅ HTTP attempt fails (405 Method Not Allowed) - expected
✅ SSE fallback succeeds - connection established
❌ MCP protocol handshake fails - timeout in client

Evidence from testing:

[8216] Using transport strategy: http-first
[8216] Received error: Error POSTing to endpoint (HTTP 405): Method Not Allowed
[8216] Recursively reconnecting for reason: falling-back-to-alternate-transport
[8216] Using transport strategy: sse-only
[8216] Connected to remote server using SSEClientTransport
[8216] Local STDIO server running
[8216] Proxy established successfully

4. Performance Comparison

Method	Speed	Reliability	Protocol	Status
smolagents MCP	0.11s	✅ Excellent	Native MCP	⭐ Best
Gradio Client	1.3s	✅ Very Good	Direct API	✅ Backup
Low-level MCP	❌ Timeout	❌ Broken	Manual MCP	❌ Don't use
HTTP Requests	❌ 405 Error	❌ Broken	REST	❌ Don't use

5. Real-World Troubleshooting

A. Import Debugging

If you have import issues, create this debugging script:

#!/usr/bin/env python3
"""Debug MCP imports"""

def check_imports():
    try:
        import smolagents.mcp_client
        print("✅ smolagents available - use smolagents approach")
        return True
    except ImportError:
        print("❌ Install: pip install 'smolagents[mcp]'")
        
    try:
        import gradio_client
        print("✅ gradio_client available - use backup approach")
        return True
    except ImportError:
        print("❌ Install: pip install gradio_client")
        
    return False

check_imports()

B. Connection Testing

Test the SSE endpoint directly in your browser:

https://freemansel-mcp-sentiment.hf.space/gradio_api/mcp/sse

You should see:

: ping - 2025-05-23 18:36:12.808434+00:00
: ping - 2025-05-23 18:36:27.809481+00:00

If you don't see pings, the Hugging Face Space might be sleeping.

C. Common Error Messages

"unhandled errors in a TaskGroup" → Use smolagents instead of low-level MCP
"HTTP 405 Method Not Allowed" → Use Gradio client instead of HTTP requests
"Connection timeout" → Check if HF Space is running, try Gradio client
"Import error: smolagents" → Install with pip install "smolagents[mcp]"

6. Ready-to-Use Scripts

Complete, tested scripts are available in the usage/ folder:

# Primary solution (fastest)
pdm run python usage/sentiment_mcp.py

# Backup solution (reliable)
pdm run python usage/sentiment_gradio.py

# Debug imports if needed
pdm run python usage/debug_imports.py

7. Cursor AI Integration

For Cursor AI, use the working smolagents approach:

{
  "mcpServers": {
    "sentiment-analysis": {
      "command": "python",
      "args": [
        "-c",
        "from smolagents.mcp_client import MCPClient; client = MCPClient({'url': 'https://freemansel-mcp-sentiment.hf.space/gradio_api/mcp/sse'}); tools = client.get_tools(); result = tools[0](text=input('Text: ')); print(f'Sentiment: {result}')"
      ]
    }
  }
}

Note: This is a simplified example. For production use, create a proper MCP server script.

8. Key Learnings from Real Testing

Always use high-level clients - smolagents.MCPClient works, low-level mcp.ClientSession doesn't
Follow official documentation - The Hugging Face MCP Course shows the right approach
Have a backup plan - Gradio client provides reliable fallback when MCP has issues
Test everything - Theoretical solutions often don't work in practice
Performance varies dramatically - smolagents (0.11s) vs Gradio (1.3s) vs broken approaches (timeout)

9. References

Hugging Face MCP Course - Use this approach
smolagents Documentation - High-level MCP client
Gradio Client Documentation - Backup approach
MCP Protocol Documentation - Low-level details

✅ This guide is based on extensive real-world testing and provides only verified, working solutions!