Skraak MCP Server

A production-ready Model Context Protocol (MCP) server implemented in Go that provides time-related tools for AI assistants.

Overview

This MCP server implements the get_current_time tool, allowing AI assistants to query the current system time with timezone information. Built using the official MCP Go SDK, it follows best practices for extensibility and maintainability.

Features

• get_current_time: Returns current system time in RFC3339 format with timezone and Unix timestamp
• Full MCP protocol compliance via stdio transport
• Type-safe tool handlers with automatic JSON schema generation
• Extensible architecture for adding new tools

Requirements

• Go 1.25.6 or later
• MCP-compatible client (Claude Desktop, etc.)

Installation

# Clone or navigate to the project directory
cd /home/david/go/src/skraak_mcp

# Download dependencies
go mod download

# Build the server
go build -o skraak_mcp

Usage

Running the Server

The server communicates over stdio (standard input/output) as per MCP specification and requires a DuckDB database path as an argument:

./skraak_mcp /path/to/database.duckdb

Example:

./skraak_mcp ./test.duckdb

Configuring with Claude Desktop

Add to your Claude Desktop MCP configuration file:

macOS: ~/Library/Application Support/Claude/claude_desktop_config.json Windows: %APPDATA%\Claude\claude_desktop_config.json Linux: ~/.config/Claude/claude_desktop_config.json

{
  "mcpServers": {
    "skraak_mcp": {
      "command": "/home/david/go/src/skraak_mcp/skraak_mcp",
      "args": ["/path/to/database.duckdb"]
    }
  }
}

Available Tools

get_current_time

Returns the current system time with comprehensive timezone information.

Input: None

Output:

{
  "time": "2024-01-25T10:30:45Z",
  "timezone": "UTC",
  "unix": 1706181045
}

Fields:

• time: Current system time in RFC3339 format (ISO 8601 compatible)
• timezone: System timezone identifier
• unix: Unix timestamp in seconds since epoch

Development

Project Structure

skraak_mcp/
├── go.mod              # Go module definition
├── go.sum              # Dependency checksums
├── main.go             # Server entry point
├── tools/              # Tool implementations
│   └── time.go        # Time-related tools
└── README.md          # This file

Adding New Tools

1. Create tool file in the tools/ package (e.g., tools/calculator.go)

2. Define input/output structures with jsonschema tags:

type CalculateInput struct {
    Expression string `json:"expression" jsonschema:"Mathematical expression to evaluate"`
}

type CalculateOutput struct {
    Result float64 `json:"result" jsonschema:"Calculated result"`
}

3. Implement handler function:

func Calculate(ctx context.Context, req *mcp.CallToolRequest, input CalculateInput) (
    *mcp.CallToolResult,
    CalculateOutput,
    error,
) {
    // Implementation
    return &mcp.CallToolResult{}, output, nil
}

4. Register in main.go:

err := mcp.AddTool(
    server,
    "calculate",
    "Evaluate mathematical expressions",
    tools.Calculate,
)

Testing

Build and test the server:

# Build
go build -o skraak_mcp

# Run (will wait for MCP protocol messages on stdin)
./skraak_mcp ./test.duckdb

# In another terminal, you can test with an MCP client
# or manually send JSON-RPC messages

Unit tests can be added in .......

Dependencies

• MCP Go SDK v1.2.0+
• DuckDB Go SDK v2

Protocol Compliance

This server implements:

• MCP Protocol version: Latest
• Transport: stdio (JSON-RPC 2.0)
• Capabilities: Tools
• Future support: Resources, Prompts

License

MIT

Contributing

Contributions welcome! Please ensure:

• Code follows Go best practices
• Tools include comprehensive descriptions
• JSON schema tags document all fields
• Error handling is robust

Troubleshooting

Server won't start:

• Check Go version: go version
• Rebuild: go build -o skraak_mcp
• Check logs in stderr

Tool not appearing in client:

• Verify MCP configuration path
• Restart Claude Desktop
• Check server binary path is correct

Time format issues:

• Output uses RFC3339 (ISO 8601) format
• Timezone reflects system configuration
• Unix timestamp is in seconds (not milliseconds)