Calculator Server - Go MCP Server

A comprehensive Go-based MCP (Model Context Protocol) server for mathematical computations, implementing 13 mathematical tools with advanced features and high precision calculations.

Owner & Maintainer: Avinash Sangle (avinash.sangle123@gmail.com)

🧮 Features

Core Mathematical Tools (13 Tools)

Basic Mathematical Tools (6 Tools)

1. Basic Math Operations - Precision arithmetic with configurable decimal places

   • Addition, subtraction, multiplication, division
   • Multiple operand support
   • Decimal precision control (0-15 places)

2. Advanced Mathematical Functions - Scientific calculations

   • Trigonometric: sin, cos, tan, asin, acos, atan
   • Logarithmic: log, log10, ln
   • Other: sqrt, abs, factorial, exp, pow
   • Unit support: degrees/radians for trig functions
   • Power function with base and exponent parameters

3. Expression Evaluation - Complex mathematical expressions

   • Variable substitution support
   • Mathematical constants (π, e)
   • Nested expressions with parentheses
   • Function calls within expressions

4. Statistical Analysis - Comprehensive data analysis

   • Descriptive statistics: mean, median, mode
   • Variability: standard deviation, variance
   • Percentile calculations
   • Data validation and error handling

5. Unit Conversion - Multi-category unit conversion

   • Length: mm, cm, m, km, in, ft, yd, mi, mil, μm, nm
   • Weight: mg, g, kg, t, oz, lb, st (stone), ton (US ton)
   • Temperature: °C, °F, K, R (Rankine)
   • Volume: ml, cl, dl, l, kl, fl_oz, cup, pt, qt, gal, tsp, tbsp, bbl
   • Area: mm², cm², m², km², in², ft², yd², mi², acre, ha

6. Financial Calculations - Comprehensive financial modeling

   • Interest calculations: simple & compound
   • Loan payment calculations
   • Return on Investment (ROI)
   • Present/Future value calculations
   • Net Present Value (NPV) & Internal Rate of Return (IRR)

Advanced Specialized Tools (7 Tools)

1. Statistics Summary - Comprehensive statistical summary of datasets

   • Complete statistical overview including all measures
   • Data preview with first/last elements
   • Common percentiles (25th, 50th, 75th)

2. Percentile Calculation - Calculate specific percentiles (0-100)

   • Any percentile value between 0 and 100
   • Data count and preview information
   • Accurate percentile calculations using empirical method

3. Batch Unit Conversion - Convert multiple values between units at once

   • Bulk conversion operations
   • Same unit categories as single conversion
   • Efficient batch processing

4. Net Present Value (NPV) - Advanced NPV calculations with cash flows

   • Multiple cash flow periods
   • Discount rate calculations
   • Investment decision support

5. Internal Rate of Return (IRR) - IRR calculations for investment analysis

   • Cash flow analysis
   • Newton-Raphson method for accurate IRR calculation
   • Investment performance evaluation

6. Loan Comparison - Compare multiple loan scenarios

   • Multiple loan option analysis
   • Payment calculations for each scenario
   • Comparison metrics and recommendations

7. Investment Scenarios - Compare multiple investment scenarios

   • Multiple investment option analysis
   • Future value calculations for each scenario
   • Investment comparison and recommendations

Technical Features

• High Precision: Uses shopspring/decimal for financial calculations
• Scientific Computing: Powered by gonum.org/v1/gonum
• Expression Engine: Advanced parsing with govaluate
• Comprehensive Testing: >95% test coverage
• Error Handling: Detailed error messages and validation
• MCP Protocol: Full compliance with MCP specification
• Build Automation: Complete Makefile with CI/CD support
• Streamable HTTP Transport: MCP-compliant HTTP transport with SSE support

🚀 Quick Start

Prerequisites

• Go 1.21+ (required)
• Git (for version control)

Installation

# Clone the repository
git clone <repository-url>
cd calculator-server

# Install dependencies
make deps

# Build the server
make build

# Run the server
make run

Alternative Setup

# Initialize Go module
go mod init calculator-server
go mod tidy

# Build and run
go build -o calculator-server ./cmd/server
./calculator-server -transport=stdio

📊 Usage Examples

Basic Mathematics

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "basic_math",
    "arguments": {
      "operation": "add",
      "operands": [15.5, 20.3, 10.2],
      "precision": 2
    }
  }
}

Response:

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "content": [
      {
        "type": "text", 
        "text": "{\"result\": 46.0}"
      }
    ]
  }
}

Advanced Mathematical Functions

{
  "jsonrpc": "2.0",
  "id": 2,
  "method": "tools/call",
  "params": {
    "name": "advanced_math",
    "arguments": {
      "function": "pow",
      "value": 2,
      "exponent": 8
    }
  }
}

Statistics Summary

{
  "jsonrpc": "2.0",
  "id": 3,
  "method": "tools/call",
  "params": {
    "name": "stats_summary",
    "arguments": {
      "data": [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
    }
  }
}

Percentile Calculation

{
  "jsonrpc": "2.0",
  "id": 4,
  "method": "tools/call",
  "params": {
    "name": "percentile",
    "arguments": {
      "data": [1, 2, 3, 4, 5, 6, 7, 8, 9, 10],
      "percentile": 90
    }
  }
}

Net Present Value

{
  "jsonrpc": "2.0",
  "id": 5,
  "method": "tools/call",
  "params": {
    "name": "npv",
    "arguments": {
      "cashFlows": [-50000, 15000, 20000, 25000, 30000],
      "discountRate": 8
    }
  }
}

Batch Unit Conversion

{
  "jsonrpc": "2.0",
  "id": 6,
  "method": "tools/call",
  "params": {
    "name": "batch_conversion",
    "arguments": {
      "values": [100, 200, 300],
      "fromUnit": "cm",
      "toUnit": "m",
      "category": "length"
    }
  }
}

🌐 MCP Streamable HTTP Transport

The server implements MCP-compliant streamable HTTP transport according to the official MCP specification, providing real-time communication with Server-Sent Events (SSE) streaming support.

MCP Protocol Compliance

✅ Single Endpoint: /mcp only (per MCP specification)
✅ Required Headers: MCP-Protocol-Version, Accept
✅ Session Management: Cryptographically secure session IDs
✅ SSE Streaming: Server-Sent Events for real-time responses
✅ CORS Support: Origin validation and security headers

HTTP Endpoints

Single MCP Endpoint (Specification Compliant)

• POST /mcp - MCP JSON-RPC with optional SSE streaming
• GET /mcp - SSE stream establishment
• OPTIONS /mcp - CORS preflight handling

Example Usage

# Start MCP-compliant HTTP server
./calculator-server -transport=http -port=8080

# Basic JSON-RPC request
curl -X POST http://localhost:8080/mcp \
  -H "Content-Type: application/json" \
  -H "Accept: application/json" \
  -H "MCP-Protocol-Version: 2024-11-05" \
  -d '{
    "jsonrpc": "2.0",
    "id": 1,
    "method": "tools/call",
    "params": {
      "name": "basic_math",
      "arguments": {
        "operation": "add",
        "operands": [15, 25],
        "precision": 2
      }
    }
  }'

# SSE streaming request (for real-time responses)
curl -X POST http://localhost:8080/mcp \
  -H "Content-Type: application/json" \
  -H "Accept: text/event-stream" \
  -H "MCP-Protocol-Version: 2024-11-05" \
  -d '{
    "jsonrpc": "2.0",
    "id": 1,
    "method": "tools/call",
    "params": {
      "name": "stats_summary",
      "arguments": {"data": [1,2,3,4,5]}
    }
  }'

🏗️ Project Structure

calculator-server/
├── cmd/
│   └── server/
│       └── main.go              # Main server entry point
├── internal/
│   ├── calculator/
│   │   ├── basic.go            # Basic math operations
│   │   ├── advanced.go         # Advanced mathematical functions
│   │   ├── expression.go       # Expression evaluation
│   │   ├── statistics.go       # Statistical analysis
│   │   ├── units.go           # Unit conversion
│   │   └── financial.go       # Financial calculations
│   ├── handlers/
│   │   ├── math_handler.go    # Math operation handlers
│   │   ├── stats_handler.go   # Statistics & specialized handlers
│   │   └── finance_handler.go # Financial handlers
│   ├── config/
│   │   ├── config.go          # Configuration structures
│   │   ├── loader.go          # Configuration loader
│   │   └── errors.go          # Configuration errors
│   └── types/
│       └── requests.go        # Request/response types
├── pkg/
│   └── mcp/
│       ├── protocol.go        # MCP protocol handling
│       └── streamable_http_transport.go # HTTP transport
├── tests/
│   ├── basic_test.go         # Basic math tests
│   ├── advanced_test.go      # Advanced math tests
│   ├── expression_test.go    # Expression evaluation tests
│   ├── integration_test.go   # Integration tests
│   ├── config_test.go        # Configuration tests
│   └── streamable_http_transport_test.go # HTTP transport tests
├── config.sample.yaml        # Sample YAML configuration
├── config.sample.json        # Sample JSON configuration
├── go.mod                    # Go module definition
├── go.sum                    # Go module checksums
├── Makefile                  # Build automation
└── README.md                 # Project documentation

🛠️ Development

Building

# Build for current platform
make build

# Build for all platforms
make build-all

# Install to $GOPATH/bin
make install

Testing

# Run all tests
make test

# Run tests with coverage
make coverage

# Run tests with race detection
make test-race

# Run benchmarks
make benchmark

Quality Assurance

# Format code
make fmt

# Run linter
make lint

# Run vet
make vet

# Run all quality checks
make quality

# Pre-commit checks
make pre-commit

# CI pipeline
make ci

Development Mode

# Run without building (development)
make run-dev

# Run with rebuild
make run

📋 Available Tools

Core Tools (6)

1. basic_math

Purpose: Basic arithmetic operations with precision control

Parameters:

• operation (string): "add", "subtract", "multiply", "divide"
• operands (array of numbers): Numbers to operate on (minimum 2)
• precision (integer, optional): Decimal places (0-15, default: 2)

2. advanced_math

Purpose: Advanced mathematical functions

Parameters:

• function (string): Function name (sin, cos, tan, asin, acos, atan, log, log10, ln, sqrt, abs, factorial, pow, exp)
• value (number): Input value (base for pow function)
• exponent (number, optional): Exponent for pow function (required for pow)
• unit (string, optional): "radians" or "degrees" for trig functions

3. expression_eval

Purpose: Evaluate mathematical expressions with variables

Parameters:

• expression (string): Mathematical expression to evaluate
• variables (object, optional): Variable name-value pairs

4. statistics

Purpose: Statistical analysis of datasets

Parameters:

• data (array of numbers): Dataset to analyze
• operation (string): Statistical operation (mean, median, mode, std_dev, variance, percentile)

5. unit_conversion

Purpose: Convert between measurement units

Parameters:

• value (number): Value to convert
• fromUnit (string): Source unit
• toUnit (string): Target unit
• category (string): Unit category (length, weight, temperature, volume, area)

6. financial

Purpose: Financial calculations and modeling

Parameters:

• operation (string): Financial operation type (compound_interest, simple_interest, loan_payment, roi, present_value, future_value)
• principal (number): Principal amount
• rate (number): Interest rate (percentage)
• time (number): Time period in years
• periods (integer, optional): Compounding periods per year
• futureValue (number, optional): Future value for some calculations

Specialized Tools (7)

7. stats_summary

Purpose: Comprehensive statistical summary of datasets

Parameters:

• data (array of numbers): Dataset for summary statistics

8. percentile

Purpose: Calculate specific percentiles

Parameters:

• data (array of numbers): Dataset to analyze
• percentile (number): Percentile to calculate (0-100)

9. batch_conversion

Purpose: Convert multiple values between units

Parameters:

• values (array of numbers): Values to convert
• fromUnit (string): Source unit
• toUnit (string): Target unit
• category (string): Unit category

10. npv

Purpose: Calculate Net Present Value

Parameters:

• cashFlows (array of numbers): Cash flows (negative for outflows, positive for inflows)
• discountRate (number): Discount rate as percentage

11. irr

Purpose: Calculate Internal Rate of Return

Parameters:

• cashFlows (array of numbers): Cash flows (minimum 2 values)

12. loan_comparison

Purpose: Compare multiple loan scenarios

Parameters:

• loans (array of objects): Loan scenarios with principal, rate, and time

13. investment_scenarios

Purpose: Compare multiple investment scenarios

Parameters:

• scenarios (array of objects): Investment scenarios with principal, rate, and time

🔧 Configuration

Command Line Options

./calculator-server [OPTIONS]

Options:
  -transport string
        Transport method (stdio, http) (default "stdio")
  -port int
        Port for HTTP transport (default 8080)
  -host string
        Host for HTTP transport (default "127.0.0.1")
  -config string
        Path to configuration file (YAML or JSON)

Examples:
  ./calculator-server                           # Run with stdio transport (default)
  ./calculator-server -transport=http          # Run with HTTP transport on port 8080
  ./calculator-server -transport=http -port=9000 -host=localhost  # Custom host/port
  ./calculator-server -config=config.yaml     # Load configuration from file

Configuration Files

The server supports configuration files in YAML and JSON formats. Configuration files are searched in the following locations:

1. Current directory (./config.yaml, ./config.json)
2. ./config/ directory
3. /etc/calculator-server/
4. $HOME/.calculator-server/

Sample YAML Configuration

server:
  transport: "http"
  http:
    host: "127.0.0.1"  # Localhost for security
    port: 8080
    session_timeout: "5m"
    max_connections: 100
    cors:
      enabled: true
      origins: ["http://localhost:3000", "http://127.0.0.1:3000"]  # Never use "*" in production

logging:
  level: "info"
  format: "json"
  output: "stdout"

tools:
  precision:
    max_decimal_places: 15
    default_decimal_places: 2
  expression_eval:
    timeout: "10s"
    max_variables: 100
  statistics:
    max_data_points: 10000
  financial:
    currency_default: "USD"

security:
  rate_limiting:
    enabled: true
    requests_per_minute: 100
  request_size_limit: "1MB"

Environment Variables

Environment variables override configuration file settings:

• CALCULATOR_TRANSPORT: Transport method (stdio, http)
• CALCULATOR_HTTP_HOST: HTTP server host
• CALCULATOR_HTTP_PORT: HTTP server port
• CALCULATOR_LOG_LEVEL: Set logging level (debug, info, warn, error)
• CALCULATOR_LOG_FORMAT: Log format (json, text)
• CALCULATOR_LOG_OUTPUT: Log output (stdout, stderr)

📈 Performance

Benchmarks

• Basic Operations: ~1-5 μs per operation
• Advanced Functions: ~10-50 μs per operation
• Expression Evaluation: ~100-500 μs per expression
• Statistical Operations: ~10-100 μs per dataset (depends on size)
• Unit Conversions: ~1-10 μs per conversion
• Financial Calculations: ~50-200 μs per calculation

Memory Usage

• Base Memory: ~10-20 MB
• Per Operation: ~1-10 KB additional
• Large Datasets: Linear scaling with data size

🧪 Testing

The project includes comprehensive tests with >95% coverage:

• Unit Tests: Test individual calculators and functions
• Integration Tests: Test MCP protocol integration
• Error Handling Tests: Validate error conditions
• Performance Tests: Benchmark critical operations

# Run specific test suites
go test ./tests/basic_test.go -v
go test ./tests/advanced_test.go -v
go test ./tests/integration_test.go -v

# Generate coverage report
make coverage

🚢 Deployment

Docker Deployment

# Build Docker image
make docker-build

# Run in Docker
make docker-run

# Push to registry
make docker-push

Binary Distribution

# Create release build
make release

# Binaries will be in ./dist/release/
ls -la ./dist/release/

📝 API Reference

MCP Protocol Support

The server implements the full MCP (Model Context Protocol) specification:

• Initialize: Server initialization and capability negotiation
• Tools List: Dynamic tool discovery
• Tools Call: Tool execution with parameter validation
• Error Handling: Comprehensive error responses

Tool Schemas

All tools include comprehensive JSON Schema definitions for parameter validation and documentation. Schemas are automatically generated and include:

• Parameter types and validation rules
• Required vs optional parameters
• Default values and constraints
• Documentation strings

📏 Unit Conversion Reference

Length Units

Unit	Abbreviation	Conversion to Meters
Millimeter	mm	0.001
Centimeter	cm	0.01
Meter	m	1.0
Kilometer	km	1000.0
Inch	in	0.0254
Foot	ft	0.3048
Yard	yd	0.9144
Mile	mi	1609.344
Mil	mil	0.0000254
Micrometer	μm	0.000001
Nanometer	nm	0.000000001

Weight/Mass Units

Unit	Abbreviation	Conversion to Grams
Milligram	mg	0.001
Gram	g	1.0
Kilogram	kg	1000.0
Metric Ton	t	1000000.0
Ounce	oz	28.3495
Pound	lb	453.592
Stone	st	6350.29
US Ton	ton	907185

Temperature Units

Unit	Abbreviation	Description
Celsius	C	Degrees Celsius
Fahrenheit	F	Degrees Fahrenheit
Kelvin	K	Kelvin (absolute)
Rankine	R	Degrees Rankine

Volume Units

Unit	Abbreviation	Conversion to Liters
Milliliter	ml	0.001
Centiliter	cl	0.01
Deciliter	dl	0.1
Liter	l	1.0
Kiloliter	kl	1000.0
US Fluid Ounce	fl_oz	0.0295735
US Cup	cup	0.236588
US Pint	pt	0.473176
US Quart	qt	0.946353
US Gallon	gal	3.78541
Teaspoon	tsp	0.00492892
Tablespoon	tbsp	0.0147868
Barrel	bbl	158.987

Area Units

Unit	Abbreviation	Conversion to m²
Square Millimeter	mm2	0.000001
Square Centimeter	cm2	0.0001
Square Meter	m2	1.0
Square Kilometer	km2	1000000.0
Square Inch	in2	0.00064516
Square Foot	ft2	0.092903
Square Yard	yd2	0.836127
Square Mile	mi2	2589988.11
Acre	acre	4046.86
Hectare	ha	10000.0

🔢 Mathematical Functions Reference

Trigonometric Functions

Function	Syntax	Description	Example
Sine	sin(x)	Sine of x (radians)	sin(pi/2) → 1.0
Cosine	cos(x)	Cosine of x (radians)	cos(0) → 1.0
Tangent	tan(x)	Tangent of x (radians)	tan(pi/4) → 1.0
Arcsine	asin(x)	Inverse sine	asin(1) → 1.5708
Arccosine	acos(x)	Inverse cosine	acos(1) → 0.0
Arctangent	atan(x)	Inverse tangent	atan(1) → 0.7854

Logarithmic Functions

Function	Syntax	Description	Example
Common Log	log(x)	Base-10 logarithm	log(100) → 2.0
Natural Log	ln(x)	Natural logarithm (base e)	ln(e) → 1.0

Power & Root Functions

Function	Syntax	Description	Example
Square Root	sqrt(x)	Square root of x	sqrt(16) → 4.0
Power	pow(x, y)	x raised to power y	pow(2, 3) → 8.0
Exponential	exp(x)	e raised to power x	exp(1) → 2.7183

Other Functions

Function	Syntax	Description	Example
Absolute Value	abs(x)	Absolute value of x	abs(-5) → 5.0
Factorial	factorial(x)	Factorial of x	factorial(5) → 120.0

Mathematical Constants

Constant	Value	Description
pi	3.14159...	Pi (π)
e	2.71828...	Euler's number

🤝 Contributing

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Commit changes (git commit -m 'Add amazing feature')
4. Push to branch (git push origin feature/amazing-feature)
5. Create a Pull Request

Development Guidelines

• Follow Go best practices and conventions
• Maintain >95% test coverage
• Add comprehensive documentation
• Use meaningful commit messages
• Run make quality before submitting

📄 License

This project is licensed under the Apache License 2.0 - see the LICENSE file for details.

🙏 Acknowledgments

• Go Team: For the excellent programming language
• MCP Protocol: Model Context Protocol specification
• External Libraries:
  • shopspring/decimal: Precise decimal arithmetic
  • Knetic/govaluate: Expression evaluation
  • gonum: Scientific computing
  • gopkg.in/yaml.v3: YAML configuration support

📞 Support & Contact

Primary Contact:

• Maintainer: Avinash Sangle
• Email: avinash.sangle123@gmail.com
• GitHub: https://github.com/avisangle
• Website: https://avisangle.github.io/

Project Resources:

• Issues: GitHub Issues
• Documentation: This README and inline code documentation
• Examples: See make example-* commands

Getting Help:

1. Check this README for comprehensive documentation
2. Review the test files for usage examples
3. Submit issues with detailed error information
4. Contact the maintainer for direct support

---

Built with ❤️ by Avinash Sangle for the IBM MCP Context Forge project

Connect with the Author:

• 🌐 Website: https://avisangle.github.io/
• 💻 GitHub: https://github.com/avisangle
• 📧 Email: avinash.sangle123@gmail.com

For more information about MCP servers and the Context Forge project, visit the IBM MCP Context Forge repository.