MCP Calculator Server

Remote MCP Server on Kubernetes (Amazon EKS)

A containerized MCP (Model Context Protocol) server using FastMCP that provides a simple calculator tool for adding two numbers. This MCP server runs on Amazon EKS. The highlevel diagram of this project below: High Level Design

Detailed walkthrough video

Files

server.py - FastMCP server with add_numbers tool
requirements.txt - Python dependencies
Dockerfile - Container definition
k8s-deployment.yaml - Kubernetes deployment and LoadBalancer service
test_mcp_client.py - Test Remote MCP Server

Building the Container

docker build -t mcp-calculator:latest .

Running Locally

# Run the container locally
docker run -p 8000:8000 mcp-calculator:latest

The server will be available at http://localhost:8000

Push to repo

You can push this image to either Dockerhub or an ECR repo

Deploying to Amazon EKS

Prerequisites

AWS CLI configured with appropriate permissions
kubectl installed
Docker installed and running

EKS Cluster

You can use an existing EKS cluster or create a new one, it's upto you. Ensure that your terminal has access to run Kubectl on it

Deployment Steps

IMPORTANT: Change the container image to the repo URI in k8s-deployment.yaml file

Deploy MCP Server container to EKS:

# Deploy the application
kubectl apply -f k8s-deployment.yaml

# Check deployment status
kubectl rollout status deployment/mcp-calculator

# Get service information
kubectl get services mcp-calculator-service

Get the LoadBalancer external IP:

kubectl get services mcp-calculator-service -w

Testing the MCP Server

The server provides one tool:

add_numbers(a: float, b: float) -> float - Adds two numbers together

Testing with curl

The MCP server is currently deployed and accessible at:

http://<insert loadbalancer url>/mcp/

Complete curl Test Workflow

Step 1: Initialize MCP Session and Get Session ID

SESSION_ID=$(curl -s -X POST \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  -d '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{"roots":{"listChanged":true},"sampling":{}},"clientInfo":{"name":"curl-test","version":"1.0.0"}}}' \
  http://<insert loadbalancer url>/mcp/ \
  -D /dev/stderr 2>&1 | grep "mcp-session-id:" | cut -d' ' -f2 | tr -d '\r')

echo "Session ID: $SESSION_ID"

Step 2: Send Initialization Notification (Required by MCP Protocol)

curl -s -X POST \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  -H "mcp-session-id: $SESSION_ID" \
  -d '{"jsonrpc":"2.0","method":"notifications/initialized"}' \
  http://<insert loadbalancer url>/mcp/

Step 3: List Available Tools (Optional)

curl -X POST \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  -H "mcp-session-id: $SESSION_ID" \
  -d '{"jsonrpc":"2.0","id":2,"method":"tools/list"}' \
  http://<insert loadbalancer url>/mcp/

Expected Result:

event: message
data: {"jsonrpc":"2.0","id":2,"result":{"tools":[{"name":"add_numbers","description":"Add two numbers together.\n\nArgs:\n    a: First number to add\n    b: Second number to add\n    \nReturns:\n    The sum of a and b","inputSchema":{"type":"object","properties":{"a":{"type":"number"},"b":{"type":"number"}},"required":["a","b"]}}]}}

Step 4: Call the add_numbers Tool

curl -X POST \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  -H "mcp-session-id: $SESSION_ID" \
  -d '{"jsonrpc":"2.0","id":3,"method":"tools/call","params":{"name":"add_numbers","arguments":{"a":15.5,"b":24.3}}}' \
  http://<insert loadbalancer url>/mcp/

Expected Result:

event: message
data: {"jsonrpc":"2.0","id":3,"result":{"content":[{"type":"text","text":"39.8"}],"structuredContent":{"result":39.8},"isError":false}}

Testing with Python client

Replace the URL in the test_mcp_client.py, and execute it. This will act as MCP client and test the MCP server

Important Notes

Session Timeout: Sessions expire after ~30-60 seconds due to FastMCP framework limitations
Rapid Execution: Execute all steps quickly or use the one-liner command
MCP Protocol: The notifications/initialized step is required by the MCP protocol after initialization

Cleanup

To remove from Kubernetes:

kubectl delete -f k8s-deployment.yaml

This server cannot be installed

security - not tested

license - not found

quality - not tested

How are these scores calculated?

A containerized MCP (Model Context Protocol) server that provides a simple calculator tool for adding two numbers, deployable to Kubernetes/EKS environments.

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