.
├── cmd
│   ├── mcpgen
│   │   └── main.go
│   └── temperature
│       └── main.go
├── mcp.gen.go
└── temperature.go

package main

import (
    "log"
    "os"
    "path/filepath"

    "github.com/ktr0731/go-mcp/codegen"
)

func main() {
    // Create output directory
    outDir := "."
    if err := os.MkdirAll(outDir, 0o755); err != nil {
        log.Fatalf("failed to create output directory: %v", err)
    }

    // Create output file
    f, err := os.Create(filepath.Join(outDir, "mcp.gen.go"))
    if err != nil {
        log.Fatalf("failed to create file: %v", err)
    }
    defer f.Close()

    // Server definition
    def := &codegen.ServerDefinition{
        Capabilities: codegen.ServerCapabilities{
            Tools:   &codegen.ToolCapability{},
            Logging: &codegen.LoggingCapability{},
        },
        Implementation: codegen.Implementation{
            Name:    "Temperature MCP Server",
            Version: "1.0.0",
        },
        // Tool definitions (declared with Go structs)
        Tools: []codegen.Tool{
            {
                Name:        "convert_temperature",
                Description: "Convert temperature between Celsius and Fahrenheit",
                InputSchema: struct {
                    Temperature float64 `json:"temperature" jsonschema:"description=Temperature value to convert"`
                    FromUnit    string  `json:"from_unit"  jsonschema:"description=Source temperature unit,enum=celsius,enum=fahrenheit"`
                    ToUnit      string  `json:"to_unit"    jsonschema:"description=Target temperature unit,enum=celsius,enum=fahrenheit"`
                }{},
            },
        },
    }

    // Generate code
    if err := codegen.Generate(f, def, "temperature"); err != nil {
        log.Fatalf("failed to generate code: %v", err)
    }
}

go run ./cmd/mcpgen

package main

import (
    "context"
    "fmt"
    "log"
    "math"

    mcp "github.com/ktr0731/go-mcp"
    "golang.org/x/exp/jsonrpc2"
)

type toolHandler struct{}

func (h *toolHandler) HandleToolConvertTemperature(ctx context.Context, req *ToolConvertTemperatureRequest) (*mcp.CallToolResult, error) {
    temperature := req.Temperature
    fromUnit := req.FromUnit
    toUnit := req.ToUnit

    var result float64
    switch {
    case fromUnit == ConvertTemperatureFromUnitTypeCelsius && toUnit == ConvertTemperatureToUnitTypeFahrenheit:
        // °C → °F: (C × 9/5) + 32
        result = (temperature*9/5 + 32)
    case fromUnit == ConvertTemperatureFromUnitTypeFahrenheit && toUnit == ConvertTemperatureToUnitTypeCelsius:
        // °F → °C: (F − 32) × 5/9
        result = (temperature - 32) * 5 / 9
    case fromUnit == toUnit:
        result = temperature
    default:
        return nil, fmt.Errorf("unsupported conversion: %s to %s", fromUnit, toUnit)
    }

    // Round to two decimal places
    result = math.Round(result*100) / 100

    resultText := fmt.Sprintf("%.2f %s = %.2f %s", temperature, fromUnit, result, toUnit)

    return &mcp.CallToolResult{
        Content: []mcp.CallToolContent{
            mcp.TextContent{Text: resultText},
        },
    }, nil
}

func main() {
    handler := NewHandler(&toolHandler{})

    ctx, listener, binder := mcp.NewStdioTransport(context.Background(), handler, nil)
    srv, err := jsonrpc2.Serve(ctx, listener, binder)
    if err != nil {
        log.Fatalf("failed to serve: %v", err)
    }

    srv.Wait()
}

go run ./cmd/temperature