Time Server Node

A comprehensive Node.js time manipulation server implementing the Model Context Protocol (MCP) for LLMs like Claude. This server provides powerful time-related operations including timezone conversions, date arithmetic, business day calculations, and more.

Features

• 🌍 Timezone Operations: Convert times between any IANA timezones
• ⏰ Current Time: Get current time in any timezone with custom formatting
• ➕➖ Date Arithmetic: Add or subtract time periods from dates
• 📊 Duration Calculations: Calculate time between dates in various units
• 💼 Business Days: Calculate business days excluding weekends and holidays
• ⏱️ Business Hours: Calculate working hours between timestamps with timezone support
• 🔄 Recurring Events: Find next occurrences of recurring patterns
• 📝 Flexible Formatting: Format times in relative, calendar, or custom formats
• 📅 Days Until: Calculate days until any date or event
• 🚀 High Performance: Response times < 10ms with intelligent caching
• 🔒 Security Hardened: Input validation, cache key hashing, ESLint security rules
• 🛡️ Rate Limiting: Configurable rate limits to prevent abuse
• ✅ Thoroughly Tested: 703+ tests with 100% coverage

Installation

Using npm (recommended)

npm install -g mcp-time-server-node

Using Claude Code (claude mcp add)

Add the server to Claude Code:

# For npm-published version (when available)
claude mcp add mcp-time-server-node

# For local development/testing
claude mcp add tim-server /path/to/mcp-time-server-node/dist/index.js

Using Claude Desktop

Manually add to your claude_desktop_config.json:

{
  "mcpServers": {
    "time-server": {
      "command": "npx",
      "args": ["-y", "mcp-time-server-node"],
      "env": {
        "NODE_ENV": "production"
      }
    }
  }
}

Local Testing

For testing before npm publish:

# Build the project
make build

# Test directly
echo '{"jsonrpc":"2.0","method":"tools/list","id":1,"params":{}}' | node dist/index.js

# Or add to Claude Code for local testing
cd mcp-time-server-node
claude mcp add time-server-local $(pwd)/dist/index.js 

Available Tools

1. get_current_time

Get the current time in any timezone.

Parameters:

• timezone (optional): IANA timezone name (default: "UTC")
• format (optional): date-fns format string
• include_offset (optional): Include UTC offset (default: true)

Example:

{
  "timezone": "America/New_York",
  "format": "yyyy-MM-dd HH:mm:ss"
}

2. convert_timezone

Convert time between timezones.

Parameters:

• time (required): Input time in ISO format or parseable string
• from_timezone (required): Source IANA timezone
• to_timezone (required): Target IANA timezone
• format (optional): Output format string

Example:

{
  "time": "2025-01-20T15:00:00Z",
  "from_timezone": "UTC",
  "to_timezone": "Asia/Tokyo"
}

3. add_time

Add a duration to a date/time.

Parameters:

• time (required): Base time
• amount (required): Amount to add
• unit (required): Unit ("years", "months", "days", "hours", "minutes", "seconds")
• timezone (optional): Timezone for calculation

Example:

{
  "time": "2025-01-20",
  "amount": 3,
  "unit": "days"
}

4. subtract_time

Subtract a duration from a date/time.

Parameters:

• Same as add_time

5. calculate_duration

Calculate the duration between two times.

Parameters:

• start_time (required): Start time
• end_time (required): End time
• unit (optional): Output unit ("auto", "milliseconds", "seconds", "minutes", "hours", "days")
• timezone (optional): Timezone for parsing

Example:

{
  "start_time": "2025-01-20T09:00:00",
  "end_time": "2025-01-20T17:30:00"
}

6. get_business_days

Calculate business days between dates.

Parameters:

• start_date (required): Start date
• end_date (required): End date
• exclude_weekends (optional): Exclude Saturdays and Sundays (default: true)
• holidays (optional): Array of holiday dates in ISO format
• timezone (optional): Timezone for calculation

Example:

{
  "start_date": "2025-01-01",
  "end_date": "2025-01-31",
  "holidays": ["2025-01-01", "2025-01-20"]
}

7. next_occurrence

Find the next occurrence of a recurring event.

Parameters:

• pattern (required): "daily", "weekly", "monthly", or "yearly"
• start_from (optional): Start searching from this date (default: now)
• day_of_week (optional): For weekly pattern (0-6, where 0 is Sunday)
• day_of_month (optional): For monthly pattern (1-31)
• time (optional): Time in HH:mm format
• timezone (optional): Timezone for calculation

Example:

{
  "pattern": "weekly",
  "day_of_week": 1,
  "time": "09:00"
}

8. format_time

Format time in various human-readable formats.

Parameters:

• time (required): Time to format
• format (required): "relative", "calendar", or "custom"
• custom_format (optional): Format string when using "custom" format
• timezone (optional): Timezone for display

Example:

{
  "time": "2025-01-20T15:00:00Z",
  "format": "relative"
}

9. calculate_business_hours

Calculate business hours between two times.

Parameters:

• start_time (required): Start time
• end_time (required): End time
• business_hours (optional): Business hours definition (default: 9 AM - 5 PM)
  • Can be a single object: { start: { hour: 9, minute: 0 }, end: { hour: 17, minute: 0 } }
  • Or weekly schedule: { 0: null, 1: { start: {...}, end: {...} }, ... } (0=Sunday, 6=Saturday)
• timezone (optional): Timezone for calculation
• holidays (optional): Array of holiday dates
• include_weekends (optional): Include weekends in calculation (default: false)

Example:

{
  "start_time": "2025-01-20T08:00:00",
  "end_time": "2025-01-24T18:00:00",
  "business_hours": {
    "start": { "hour": 9, "minute": 0 },
    "end": { "hour": 17, "minute": 30 }
  },
  "holidays": ["2025-01-22"],
  "timezone": "America/New_York"
}

10. days_until

Calculate days until a target date or event.

Parameters:

• target_date (required): Target date (ISO string, natural language like "next Christmas", or Unix timestamp)
• timezone (optional): Timezone for calculation (default: system timezone)
• format_result (optional): Return formatted string instead of number (default: false)

Example:

{
  "target_date": "2025-12-25",
  "timezone": "America/New_York"
}

Environment Variables

• NODE_ENV: Set to "production" for production use
• RATE_LIMIT: Maximum requests per minute (default: 100)
• RATE_LIMIT_WINDOW: Rate limit window in milliseconds (default: 60000)
• CACHE_SIZE: Maximum cache entries (default: 10000)
• DEFAULT_TIMEZONE: Override system timezone detection (e.g., "America/New_York")
• MAX_LISTENERS: Maximum concurrent requests (default: 20, minimum: 10)

Performance

• All operations complete in < 10ms (after initial load)
• Intelligent caching reduces repeated calculations
• Sliding window rate limiting prevents abuse
• Memory-efficient implementation

Error Handling

The server returns structured errors with codes:

• INVALID_TIMEZONE: Invalid timezone specified
• INVALID_DATE_FORMAT: Cannot parse the provided date
• INVALID_UNIT: Invalid time unit specified
• RATE_LIMIT_EXCEEDED: Too many requests
• INVALID_RECURRENCE_PATTERN: Invalid recurrence pattern

Development

Current Status

Refactoring completed

Building from source

git clone https://github.com/pshempel/mcp-time-node.git
cd mcp-time-server-node
make setup    # Install dependencies and build
make test     # Run all tests

Running tests

make test         # Run all tests
make coverage     # Run with coverage report
make test-watch   # Run in watch mode for TDD

# If tests fail unexpectedly:
make test-quick   # Fix Jest issues and run tests
make reset        # Full environment reset

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

MIT License - see LICENSE file for details

Author

pshempel

Acknowledgments

Built with:

• Model Context Protocol SDK
• date-fns for date manipulation
• date-fns-tz for timezone support