Add usage documentation and example for JSON serialization configuration

Co-authored-by: eiriktsarpalis <2813363+eiriktsarpalis@users.noreply.github.com>

Author: Copilot

USAGE_EXAMPLE.md

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+# JSON Serialization Configuration for MCP Server
+
+This document demonstrates how to configure JSON serialization options for your MCP server to handle special cases like `double.Infinity` or `NaN` values.
+
+## Problem
+
+By default, JSON serialization in .NET doesn't support special floating-point values like positive/negative infinity and NaN. When a tool returns such values, you would get an error:
+
+```
+System.ArgumentException: .NET number values such as positive and negative infinity cannot be written as valid JSON. 
+To make it work when using 'JsonSerializer', consider specifying 'JsonNumberHandling.AllowNamedFloatingPointLiterals'
+```
+
+## Solution
+
+Configure server-wide JSON serialization options when setting up your MCP server:
+
+```csharp
+using Microsoft.Extensions.DependencyInjection;
+using ModelContextProtocol.Server;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+var builder = WebApplication.CreateBuilder(args);
+
+// Configure server-wide JSON serialization options
+builder.Services.AddMcpServer(options =>
+{
+    options.JsonSerializerOptions = new JsonSerializerOptions(McpJsonUtilities.DefaultOptions)
+    {
+        NumberHandling = JsonNumberHandling.AllowNamedFloatingPointLiterals
+    };
+})
+.WithTools<MyTools>();
+
+var app = builder.Build();
+app.Run();
+
+[McpServerToolType]
+public class MyTools
+{
+    [McpServerTool]
+    public static double[] GetSpecialNumbers()
+    {
+        // These values will now serialize correctly as "Infinity", "-Infinity", and "NaN"
+        return new[] { double.PositiveInfinity, double.NegativeInfinity, double.NaN };
+    }
+}
+```
+
+## How It Works
+
+1. The `JsonSerializerOptions` property on `McpServerOptions` provides server-wide default serialization settings
+2. All tools, prompts, and resources registered via `WithTools*`, `WithPrompts*`, and `WithResources*` will use these options by default
+3. Individual registrations can still override with their own specific options if needed
+
+## Override for Specific Tools
+
+If you need different serialization options for specific tools, you can still provide them explicitly:
+
+```csharp
+var customOptions = new JsonSerializerOptions
+{
+    PropertyNamingPolicy = JsonNamingPolicy.SnakeCaseLower
+};
+
+builder.Services.AddMcpServer(options =>
+{
+    options.JsonSerializerOptions = McpJsonUtilities.DefaultOptions; // Default for most tools
+})
+.WithTools<MyTools>() // Uses server-wide options
+.WithTools<SpecialTools>(customOptions); // Uses custom options
+```
+
+## Additional Configuration Options
+
+You can configure other JSON serialization settings as needed:
+
+```csharp
+options.JsonSerializerOptions = new JsonSerializerOptions(McpJsonUtilities.DefaultOptions)
+{
+    NumberHandling = JsonNumberHandling.AllowNamedFloatingPointLiterals,
+    PropertyNameCaseInsensitive = true,
+    AllowTrailingCommas = true,
+    WriteIndented = true // For debugging
+};
+```