MCP HelloWorld for Code Exchange – integrated MCP Inspector Demo

MCP HelloWorld for Code Exchange with web MCP Inspector. This repo contains a tiny FastMCP server and a simple demo that you can run locally or instantly in Cisco DevNet CodeExchange DevEnv. It showcases three small tools that are handy for quick testing and network workflows: roll_dice (random dice), nslookup (DNS lookup wrapper), and cidr_info_ipv4 (IPv4 subnet facts). Use the "Run MCP Inspector IDE in Cloud" button to launch a preconfigured environment, then open the included MCP Inspector to invoke the tools.

Demo

Load MCPs

Instantly connect your MCP server to the Inspector and work side-by-side—no window-switching needed.

Show tools

Explore all available MCP tools through the Inspector's intuitive GUI for a seamless discovery experience.

Run live tests

Select any tool, add inputs, and execute—bringing your entire build-deploy-test loop together in one place.

Try it in Cisco DevNet DevEnv (no local setup)

Click to launch a browser-based environment with this repo pre-cloned and FastMCP preinstalled:

Once the DevEnv opens:

• Change working dir cd mcp-helloworld-code-exch
• Install requirements pip install -r requirements.txt
• Start the server (HTTP on 9000) if needed: python demo_mcp.py
  • MCP server endpoint: http://127.0.0.1:9000/mcp (transport: streamable-http)
• On right side of IDE in MCP Inspector, configure below settings and Connect to local MCP server.
  • Transport Type : Streamable HTTP
  • URL : http://127.0.0.1:9000/mcp
• Go to Tools tab, list tools, and try out:
  • roll_dice
  • nslookup
  • cidr_info_ipv4

Local run (quick)

If you prefer local instead of DevEnv:

python3 -m venv .venv
source .venv/bin/activate
python -m pip install -r requirements.txt
python demo_mcp.py

What this demo provides

• roll_dice(sides=6, rolls=1): Returns individual dice results and total.
• nslookup(name, record?, server?, timeout=5.0): Wraps the system nslookup for quick DNS checks. Returns ok, exit_code, command, stdout, stderr.
• cidr_info_ipv4(cidr): IPv4-only CIDR facts like netmask, wildcard, first/last IP, and total addresses.

Requirements

• nslookup available on your system (macOS has it by default). Verify with: which nslookup.

Run as HTTP (Streamable) on port 9000

The script is configured to start an HTTP MCP server on http://127.0.0.1:9000/mcp.

source .venv/bin/activate
python demo_mcp.py

Health checks / quick probes:

• Base server: curl -i http://127.0.0.1:9000/
• MCP endpoint (expects MCP client payloads): curl -i http://127.0.0.1:9000/mcp (GET may return 406; that still confirms the endpoint is up.)

Tool reference

cidr_info_ipv4

Input:

{ "cidr": "10.0.0.0/24" }

Output:

{
  "cidr": "10.0.0.0/24",
  "netmask": "255.255.255.0",
  "wildcard": "0.0.0.255",
  "first_ip": "10.0.0.0",
  "last_ip": "10.0.0.255",
  "total_hosts": 256
}

nslookup

Inputs (examples):

{ "name": "example.com" }
{ "name": "example.com", "record": "AAAA" }
{ "name": "example.com", "record": "A", "server": "8.8.8.8" }

roll_dice

Input:

{ "rolls": 3 }

Output:

{ "sides": 6, "rolls": 3, "results": [2, 6, 5], "total": 13 }