Running this sample

You're recommended to install uv but it's not a must, see instructions

-0- Create a virtual environment

python -m venv venv

-1- Activate the virtual environment

venv\Scripts\activate

-2- Install the dependencies

pip install "mcp[cli]"

-3- Run the sample

mcp run server.py

-4- Test the sample

With the server running in one terminal, open another terminal and run the following command:

mcp dev server.py

This should start a web server with a visual interface allowing you to test the sample.

Once the server is connected:

try listing tools and run add, with args 2 and 4, you should see 6 in the result.
go to resources and resource template and call get_greeting, type in a name and you should see a greeting with the name you provided.

Testing in ClI mode

The inspector you ran is actually a Node.js app and mcp dev is a wrapper around it.

You can launch it directly in CLI mode by running the following command:

npx @modelcontextprotocol/inspector --cli mcp run server.py --method tools/list

This will list all the tools available in the server. You should see the following output:

{
  "tools": [
    {
      "name": "add",
      "description": "Add two numbers",
      "inputSchema": {
        "type": "object",
        "properties": {
          "a": {
            "title": "A",
            "type": "integer"
          },
          "b": {
            "title": "B",
            "type": "integer"
          }
        },
        "required": [
          "a",
          "b"
        ],
        "title": "addArguments"
      }
    }
  ]
}

To invoke a tool type:

npx @modelcontextprotocol/inspector --cli mcp run server.py --method tools/call --tool-name add --tool-arg a=1 --tool-arg b=2

You should see the following output:

{
  "content": [
    {
      "type": "text",
      "text": "3"
    }
  ],
  "isError": false
}

Tip

It's usually a lot faster to run the ispector in CLI mode than in the browser. Read more about the inspector here.

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