MCP Testbed

This project demonstrates sentiment analysis using the Model Context Protocol (MCP) and is based on the Hugging Face MCP Course. Instead of using the gradio library in the HuggingFace course, this project utilizes the fastmcp library to implement an MCP server and client.

Folder Structure

• mcp-sentiment/app_fastmcp.py: MCP server script for sentiment analysis.
• mcp-sentiment/mcp_client_stdio.py: MCP client that connects to the server and requests sentiment analysis via command line.
• mcp-sentiment/mcp_client_sse.py: MCP client that connects to the server and requests sentiment analysis via SSE transport.

Usage

To run sentiment analysis from the command line using stdio transport:

python mcp-sentiment/mcp_client_stdio.py "Your text to test sentiment"

To run sentiment analysis from the command line using SSE transport:

python mcp-sentiment/mcp_client_sse.py "Your text to test sentiment"

If no text is provided, the program will exit with an error message.

How It Works

The application uses Model Context Protocol (MCP) to facilitate communication between a client and a sentiment analysis server. When you run the client with a text string, it:

1. Connects to the server script (app_fastmcp.py) or SSE endpoint
2. Sends your text for sentiment analysis
3. Returns the sentiment result (positive, negative, or neutral)

Server (app_fastmcp.py)

The app_fastmcp.py file implements an MCP server using FastMCP that:

• Exposes a sentiment analysis tool via the Model Context Protocol
• Uses TextBlob library to analyze sentiment of provided text
• Returns JSON results with:
  • Polarity score (-1 to 1, negative to positive)
  • Subjectivity score (0 to 1, objective to subjective)
  • Overall assessment (positive, negative, or neutral)
• Supports stdio or ssetransport for communication with clients

Client (mcp_client_stdio.py)

The mcp_client_stdio.py file implements an MCP client that:

• Accepts text input from the command line
• Establishes a connection to the MCP server using stdio transport
• Lists available tools on the connected server
• Sends the input text to the sentiment_analysis tool
• Receives and displays the JSON response with sentiment results
• Properly manages resources with async context managers

Client (mcp_client_sse.py)

The mcp_client_sse.py file implements an MCP client that:

• Accepts text input from the command line
• Establishes a connection to the MCP server using SSE transport
• Lists available tools on the connected server
• Sends the input text to the sentiment_analysis tool
• Receives and displays the JSON response with sentiment results
• Properly manages resources with async context managers

Example Usage with stdio Transport

((venv) ) Mac:jim mcp_testlab[520]$ python mcp-sentiment/mcp_client_stdio.py "I love python"
```bash
((venv) ) Mac:jim mcp_testlab[520]$ python mcp-sentiment/mcp_client_stdio.py "I love python"

Connected to MCP server. Listing available tools...
[07/27/25 23:34:42] INFO     Processing request of type ListToolsRequest                                                                                                                       server.py:619

tools: ['sentiment_analysis']
                    INFO     Processing request of type CallToolRequest                                                                                                                        server.py:619

Sentiment Analysis Result: [TextContent(type='text', text='{"polarity": 0.5, "subjectivity": 0.6, "assessment": "positive"}', annotations=None, meta=None)]


((venv) ) Mac:jim mcp_testlab[523]$ python mcp-sentiment/mcp_client_stdio.py "I hate python"

Connected to MCP server. Listing available tools...
[07/27/25 23:36:35] INFO     Processing request of type ListToolsRequest                                                                                                                       server.py:619

tools: ['sentiment_analysis']
                    INFO     Processing request of type CallToolRequest                                                                                                                        server.py:619

Sentiment Analysis Result: [TextContent(type='text', text='{"polarity": -0.8, "subjectivity": 0.9, "assessment": "negative"}', annotations=None, meta=None)]
((venv) ) Mac:jim mcp_testlab[524]$ 

Example Usage with sse Transport

Client

((venv) ) Mac:jim mcp_testlab[516]$ python mcp-sentiment/mcp_client_sse.py "I love kittens"

Connected to MCP server. Listing available tools...

tools: ['sentiment_analysis']

Sentiment Analysis Result: [TextContent(type='text', text='{"polarity": 0.5, "subjectivity": 0.6, "assessment": "positive"}', annotations=None, meta=None)]


((venv) ) Mac:jim mcp_testlab[517]$ python mcp-sentiment/mcp_client_sse.py "this movie is terrible, a waste of money"

Connected to MCP server. Listing available tools...

tools: ['sentiment_analysis']

Sentiment Analysis Result: [TextContent(type='text', text='{"polarity": -0.6, "subjectivity": 0.5, "assessment": "negative"}', annotations=None, meta=None)]
((venv) ) Mac:jim mcp_testlab[518]$ ```

SSE Server

((venv) ) Mac:jim mcp_testlab[517]$ python mcp-sentiment/app_fastmcp.py --transport sse
INFO:     Started server process [34093]
INFO:     Waiting for application startup.
INFO:     Application startup complete.
INFO:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
INFO:     127.0.0.1:50141 - "GET /sse HTTP/1.1" 200 OK
INFO:     127.0.0.1:50143 - "POST /messages/?session_id=8a3facb39d544dca8acc9cd9af4893d9 HTTP/1.1" 202 Accepted
INFO:     127.0.0.1:50143 - "POST /messages/?session_id=8a3facb39d544dca8acc9cd9af4893d9 HTTP/1.1" 202 Accepted
INFO:     127.0.0.1:50143 - "POST /messages/?session_id=8a3facb39d544dca8acc9cd9af4893d9 HTTP/1.1" 202 Accepted
[07/28/25 06:51:02] INFO     Processing request of type ListToolsRequest                                                                                                                                               server.py:619
INFO:     127.0.0.1:50143 - "POST /messages/?session_id=8a3facb39d544dca8acc9cd9af4893d9 HTTP/1.1" 202 Accepted
                    INFO     Processing request of type CallToolRequest                                                                                                                                                server.py:619
INFO:     127.0.0.1:50146 - "GET /sse HTTP/1.1" 200 OK
INFO:     127.0.0.1:50148 - "POST /messages/?session_id=68de3cfbb3b7440194c7884e42d85d3c HTTP/1.1" 202 Accepted
INFO:     127.0.0.1:50148 - "POST /messages/?session_id=68de3cfbb3b7440194c7884e42d85d3c HTTP/1.1" 202 Accepted
INFO:     127.0.0.1:50148 - "POST /messages/?session_id=68de3cfbb3b7440194c7884e42d85d3c HTTP/1.1" 202 Accepted
[07/28/25 06:51:06] INFO     Processing request of type ListToolsRequest                                                                                                                                               server.py:619
INFO:     127.0.0.1:50148 - "POST /messages/?session_id=68de3cfbb3b7440194c7884e42d85d3c HTTP/1.1" 202 Accepted
                    INFO     Processing request of type CallToolRequest                                                                                                                                                server.py:619
^CINFO:     Shutting down
INFO:     Waiting for application shutdown.
INFO:     Application shutdown complete.
INFO:     Finished server process [34093]
Traceback (most recent call last):
  File "/opt/homebrew/Cellar/python@3.12/3.12.11/Frameworks/Python.framework/Versions/3.12/lib/python3.12/asyncio/runners.py", line 118, in run
    return self._loop.run_until_complete(task)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/homebrew/Cellar/python@3.12/3.12.11/Frameworks/Python.framework/Versions/3.12/lib/python3.12/asyncio/base_events.py", line 691, in run_until_complete
    return future.result()
           ^^^^^^^^^^^^^^^
asyncio.exceptions.CancelledError

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/jim/Desktop/modelcontextprotocol/mcp_testlab/mcp-sentiment/app_fastmcp.py", line 52, in <module>
    mcp.run(transport=args.transport)
  File "/Users/jim/Desktop/modelcontextprotocol/mcp_testlab/venv/lib/python3.12/site-packages/mcp/server/fastmcp/server.py", line 228, in run
    anyio.run(lambda: self.run_sse_async(mount_path))
  File "/Users/jim/Desktop/modelcontextprotocol/mcp_testlab/venv/lib/python3.12/site-packages/anyio/_core/_eventloop.py", line 74, in run
    return async_backend.run(func, args, {}, backend_options)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/jim/Desktop/modelcontextprotocol/mcp_testlab/venv/lib/python3.12/site-packages/anyio/_backends/_asyncio.py", line 2310, in run
    return runner.run(wrapper())
           ^^^^^^^^^^^^^^^^^^^^^
  File "/opt/homebrew/Cellar/python@3.12/3.12.11/Frameworks/Python.framework/Versions/3.12/lib/python3.12/asyncio/runners.py", line 123, in run
    raise KeyboardInterrupt()
KeyboardInterrupt

MCP Inspector

The MCP Inspector is a tool for exploring and interacting with Model Context Protocol (MCP) servers. It provides a user-friendly interface for:

• Discovering available tools and their capabilities
• Sending requests to tools and viewing responses
• Debugging and testing MCP interactions

Running MCP Inspector with stdio Transport

To run the MCP Inspector for server using stdio transport, use the following command:

mcp dev mcp-sentiment/app_fastmcp.py

Sample output will show the available tools and their descriptions, allowing you to interact with the sentiment analysis tool.

MCP Inspector Listing Tools

MCP Inspector Testing Sentiment Analysis

Running MCP Inspector with sse Transport

Starting the sse Server for testing

python mcp-sentiment/app_fastmcp.py --transport sse

To run the MCP Inspector for server using sse transport, use the following command:

npx @modelcontextprotocol/inspector

Connecting to the MCP Inspector

Open the browser to access the MCP Inspector interface, change from http to https if necessary. Once the MCP Inspector is running, configure "Transport Type" for sse and set the server URL to point to your running MCP server (e.g., http://localhost:8000/sse) and click "Connect" button.

MCP Inspector Testing Sentiment Analysis

Requirements

• Python 3.12+
• Dependencies: pip install -r requirements.txt
• Required NLP libraries for sentiment analysis
• Required version of node > v20.x to run MCP Inspector (see GH Issue on unexpected token)