implement NewTypedToolHandlerFunc

Author: ezynda3

examples/typed_tools/main.go

@@ -0,0 +1,105 @@
+package main
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/mark3labs/mcp-go/mcp"
+	"github.com/mark3labs/mcp-go/server"
+)
+
+// Define a struct for our typed arguments
+type GreetingArgs struct {
+	Name      string   `json:"name"`
+	Age       int      `json:"age"`
+	IsVIP     bool     `json:"is_vip"`
+	Languages []string `json:"languages"`
+	Metadata  struct {
+		Location string `json:"location"`
+		Timezone string `json:"timezone"`
+	} `json:"metadata"`
+}
+
+func main() {
+	// Create a new MCP server
+	s := server.NewMCPServer(
+		"Typed Tools Demo 🚀",
+		"1.0.0",
+		server.WithToolCapabilities(false),
+	)
+
+	// Add tool with complex schema
+	tool := mcp.NewTool("greeting",
+		mcp.WithDescription("Generate a personalized greeting"),
+		mcp.WithString("name",
+			mcp.Required(),
+			mcp.Description("Name of the person to greet"),
+		),
+		mcp.WithNumber("age",
+			mcp.Description("Age of the person"),
+			mcp.Min(0),
+			mcp.Max(150),
+		),
+		mcp.WithBoolean("is_vip",
+			mcp.Description("Whether the person is a VIP"),
+			mcp.DefaultBool(false),
+		),
+		mcp.WithArray("languages",
+			mcp.Description("Languages the person speaks"),
+			mcp.Items(map[string]any{"type": "string"}),
+		),
+		mcp.WithObject("metadata",
+			mcp.Description("Additional information about the person"),
+			mcp.Properties(map[string]any{
+				"location": map[string]any{
+					"type":        "string",
+					"description": "Current location",
+				},
+				"timezone": map[string]any{
+					"type":        "string",
+					"description": "Timezone",
+				},
+			}),
+		),
+	)
+
+	// Add tool handler using the typed handler
+	s.AddTool(tool, mcp.NewTypedToolHandler(typedGreetingHandler))
+
+	// Start the stdio server
+	if err := server.ServeStdio(s); err != nil {
+		fmt.Printf("Server error: %v\n", err)
+	}
+}
+
+// Our typed handler function that receives strongly-typed arguments
+func typedGreetingHandler(ctx context.Context, request mcp.CallToolRequest, args GreetingArgs) (*mcp.CallToolResult, error) {
+	if args.Name == "" {
+		return mcp.NewToolResultError("name is required"), nil
+	}
+
+	// Build a personalized greeting based on the complex arguments
+	greeting := fmt.Sprintf("Hello, %s!", args.Name)
+	
+	if args.Age > 0 {
+		greeting += fmt.Sprintf(" You are %d years old.", args.Age)
+	}
+	
+	if args.IsVIP {
+		greeting += " Welcome back, valued VIP customer!"
+	}
+	
+	if len(args.Languages) > 0 {
+		greeting += fmt.Sprintf(" You speak %d languages: %v.", len(args.Languages), args.Languages)
+	}
+	
+	if args.Metadata.Location != "" {
+		greeting += fmt.Sprintf(" I see you're from %s.", args.Metadata.Location)
+		
+		if args.Metadata.Timezone != "" {
+			greeting += fmt.Sprintf(" Your timezone is %s.", args.Metadata.Timezone)
+		}
+	}
+
+	return mcp.NewToolResultText(greeting), nil
+}

mcp/tools.go

@@ -46,8 +46,8 @@ type CallToolResult struct {
 type CallToolRequest struct {
 	Request
 	Params struct {
-		Name      string      `json:"name"`
-		Arguments any `json:"arguments,omitempty"` // Can be map[string]any or any other type
+		Name      string `json:"name"`
+		Arguments any    `json:"arguments,omitempty"` // Can be map[string]any or any other type
 		Meta      *struct {
 			// If specified, the caller is requesting out-of-band progress
 			// notifications for this request (as represented by

mcp/typed_tools.go

@@ -0,0 +1,20 @@
+package mcp
+
+import (
+	"context"
+	"fmt"
+)
+
+// TypedToolHandlerFunc is a function that handles a tool call with typed arguments
+type TypedToolHandlerFunc[T any] func(ctx context.Context, request CallToolRequest, args T) (*CallToolResult, error)
+
+// NewTypedToolHandler creates a ToolHandlerFunc that automatically binds arguments to a typed struct
+func NewTypedToolHandler[T any](handler TypedToolHandlerFunc[T]) func(ctx context.Context, request CallToolRequest) (*CallToolResult, error) {
+	return func(ctx context.Context, request CallToolRequest) (*CallToolResult, error) {
+		var args T
+		if err := request.BindArguments(&args); err != nil {
+			return NewToolResultError(fmt.Sprintf("failed to bind arguments: %v", err)), nil
+		}
+		return handler(ctx, request, args)
+	}
+}