refactor(demo): update calculator demo to use functional tool

Author: salty-flower

src/ModelContextProtocol.NET.Demo.Calculator/ModelContextProtocol.NET.Demo.Calculator.csproj

@@ -12,6 +12,9 @@
     <PackageReference Include="Serilog" />
     <PackageReference Include="Serilog.Extensions.Logging" />
     <PackageReference Include="Serilog.Sinks.File" />
+    <ProjectReference
+      Include="..\ModelContextProtocol.NET.Core\ModelContextProtocol.NET.Core.csproj"
+    />
     <ProjectReference
       Include="..\ModelContextProtocol.NET.Server\ModelContextProtocol.NET.Server.csproj"
     />

src/ModelContextProtocol.NET.Demo.Calculator/Program.cs

@@ -1,7 +1,11 @@
-using System.Threading.Tasks;
+using System;
+using System.Threading;
+using System.Threading.Tasks;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
+using ModelContextProtocol.NET.Core.Models.Protocol.Client.Responses;
 using ModelContextProtocol.NET.Core.Models.Protocol.Common;
+using ModelContextProtocol.NET.Core.Models.Protocol.Shared.Content;
 using ModelContextProtocol.NET.Demo.Calculator.Handlers;
 using ModelContextProtocol.NET.Server.Builder;
 using Serilog;
@@ -25,7 +29,42 @@
             builder.SetMinimumLevel(LogLevel.Trace);
         })
     )
-    .ConfigureTools(tools => tools.AddHandler<CalculatorToolHandler>())
+    .ConfigureTools(tools =>
+        tools
+        //.AddHandler<CalculatorToolHandler>()
+        .AddFunction(
+            name: "Calculator_function_flavor",
+            description: "Still performs basic arithmetic operations, but implemented in functional style",
+            parameterTypeInfo: CalculatorParametersJsonContext.Default.CalculatorParameters,
+            handler: (CalculatorParameters parameters, CancellationToken ct) =>
+                Task.FromResult(
+                    new CallToolResult
+                    {
+                        Content = (TextContent)
+                            (
+                                (double)(
+                                    parameters.Operation switch
+                                    {
+                                        CalculatorOperation.Add => parameters.A + parameters.B,
+                                        CalculatorOperation.Subtract => parameters.A - parameters.B,
+                                        CalculatorOperation.Multiply => parameters.A * parameters.B,
+                                        CalculatorOperation.Divide when parameters.B != 0
+                                            => parameters.A / parameters.B,
+                                        CalculatorOperation.Divide
+                                            => throw new DivideByZeroException(
+                                                "Cannot divide by zero"
+                                            ),
+                                        _
+                                            => throw new ArgumentException(
+                                                $"Unknown operation: {parameters.Operation}"
+                                            ),
+                                    }
+                                )
+                            ).ToString()
+                    }
+                )
+        )
+    )
     .Build();
 
 try