Add 15 MCP tools for book content, listings, guidelines, and search

- Add IGuidelinesService + GuidelinesService (singleton) for guidelines.json
- Add BookListingTool: GetListingSourceCode, SearchListingsByCode
- Add BookGuidelinesTool: GetCSharpGuidelines, GetGuidelinesByTopic
- Add BookContentTool: GetSectionContent, GetListingWithContext,
  GetNavigationContext, GetChapterSummary
- Extend BookSearchTool: GetChapterSections, GetDirectContentUrl,
  GetBookMetadata, LookupConcept, CheckTopicCoverage,
  FindBookHelpForDiagnostic, FindRelatedSections
- Register all new tools in Program.cs MCP block

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: BenjaminMichaelis

EssentialCSharp.Chat.Shared/Services/AIChatService.cs

@@ -354,22 +354,17 @@ private static async Task<ResponseCreationOptions> CreateResponseOptionsAsync(
                     Dictionary<string, object?> arguments = [];
                     foreach (var kvp in jsonArguments)
                     {
-                        if (kvp.Value is System.Text.Json.JsonElement jsonElement)
-                        {
-                            arguments[kvp.Key] = jsonElement.ValueKind switch
+                        arguments[kvp.Key] = kvp.Value is System.Text.Json.JsonElement jsonElement
+                            ? jsonElement.ValueKind switch
                             {
                                 System.Text.Json.JsonValueKind.String => jsonElement.GetString(),
                                 System.Text.Json.JsonValueKind.Number => jsonElement.GetDecimal(),
                                 System.Text.Json.JsonValueKind.True => true,
                                 System.Text.Json.JsonValueKind.False => false,
                                 System.Text.Json.JsonValueKind.Null => null,
-                                _ => jsonElement.ToString()
-                            };
-                        }
-                        else
-                        {
-                            arguments[kvp.Key] = kvp.Value;
-                        }
+                                _ => (object?)jsonElement.ToString()
+                            }
+                            : kvp.Value;
                     }
 
                     var toolResult = await mcpClient.CallToolAsync(

EssentialCSharp.Web.Tests/McpTests.cs

@@ -31,7 +31,7 @@ public async Task McpEndpoint_WithoutToken_Returns401()
     {
         HttpClient client = factory.CreateClient();
 
-        var request = CreateMcpInitializeRequest("/mcp");
+        using var request = CreateMcpInitializeRequest("/mcp");
         using HttpResponseMessage response = await client.SendAsync(request);
 
         await Assert.That(response.StatusCode).IsEqualTo(HttpStatusCode.Unauthorized);
@@ -65,7 +65,7 @@ public async Task McpEndpoint_WithValidToken_Returns200AndListsTools()
         HttpClient client = factory.CreateClient();
 
         // Step 1: Initialize the MCP session
-        var initRequest = CreateMcpInitializeRequest("/mcp");
+        using var initRequest = CreateMcpInitializeRequest("/mcp");
         initRequest.Headers.Authorization = new AuthenticationHeaderValue("Bearer", rawToken);
 
         using HttpResponseMessage initResponse = await client.SendAsync(initRequest);
@@ -77,7 +77,7 @@ public async Task McpEndpoint_WithValidToken_Returns200AndListsTools()
             sessionId = sessionIdValues.First();
 
         // Step 2: List tools
-        var listToolsRequest = new HttpRequestMessage(HttpMethod.Post, "/mcp")
+        using var listToolsRequest = new HttpRequestMessage(HttpMethod.Post, "/mcp")
         {
             Content = new StringContent(
                 """{"jsonrpc":"2.0","id":2,"method":"tools/list","params":{}}""",
@@ -116,7 +116,7 @@ public async Task McpEndpoint_WithValidToken_Returns200AndListsTools()
     public async Task McpEndpoint_WithInvalidToken_Returns401()
     {
         HttpClient client = factory.CreateClient();
-        var request = CreateMcpInitializeRequest("/mcp");
+        using var request = CreateMcpInitializeRequest("/mcp");
         request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", "mcp_invalid_token_that_does_not_exist");
         using HttpResponseMessage response = await client.SendAsync(request);
         await Assert.That(response.StatusCode).IsEqualTo(HttpStatusCode.Unauthorized);
@@ -147,7 +147,7 @@ public async Task McpEndpoint_WithRevokedToken_Returns401()
         }
 
         HttpClient client = factory.CreateClient();
-        var request = CreateMcpInitializeRequest("/mcp");
+        using var request = CreateMcpInitializeRequest("/mcp");
         request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", rawToken);
         using HttpResponseMessage response = await client.SendAsync(request);
         await Assert.That(response.StatusCode).IsEqualTo(HttpStatusCode.Unauthorized);
@@ -179,7 +179,7 @@ public async Task McpEndpoint_WithExpiredToken_Returns401()
         }
 
         HttpClient client = factory.CreateClient();
-        var request = CreateMcpInitializeRequest("/mcp");
+        using var request = CreateMcpInitializeRequest("/mcp");
         request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", rawToken);
         using HttpResponseMessage response = await client.SendAsync(request);
         await Assert.That(response.StatusCode).IsEqualTo(HttpStatusCode.Unauthorized);

EssentialCSharp.Web/Controllers/McpTokenController.cs

@@ -26,12 +26,12 @@ public async Task<IActionResult> CreateToken(
             return BadRequest(new { Error = "Token name must be 256 characters or fewer." });
 
         DateTime? expiresAt = null;
-        if (request?.ExpiresOn.HasValue == true)
+        if (request?.ExpiresOn is DateOnly expiresOn)
         {
-            if (request.ExpiresOn.Value < DateOnly.FromDateTime(DateTime.UtcNow))
+            if (expiresOn < DateOnly.FromDateTime(DateTime.UtcNow))
                 return BadRequest(new { Error = "ExpiresOn must be today or in the future." });
             // Convert date-only boundary to end-of-day UTC instant before persisting
-            expiresAt = request.ExpiresOn.Value.ToDateTime(TimeOnly.MaxValue, DateTimeKind.Utc);
+            expiresAt = expiresOn.ToDateTime(TimeOnly.MaxValue, DateTimeKind.Utc);
         }
 
         var (rawToken, entity) = await tokenService.CreateTokenAsync(

EssentialCSharp.Web/Program.cs

@@ -260,9 +260,14 @@ private static void Main(string[] args)
                 policy.AddAuthenticationSchemes("McpBearer")
                       .RequireAuthenticatedUser()));
 
+        builder.Services.AddSingleton<IGuidelinesService, GuidelinesService>();
+
         builder.Services.AddMcpServer()
             .WithHttpTransport(options => options.Stateless = true)
-            .WithTools<BookSearchTool>();
+            .WithTools<BookSearchTool>()
+            .WithTools<BookListingTool>()
+            .WithTools<BookGuidelinesTool>()
+            .WithTools<BookContentTool>();
 
         // Add Rate Limiting for API endpoints
         builder.Services.AddRateLimiter(options =>

EssentialCSharp.Web/Services/GuidelinesService.cs

@@ -0,0 +1,16 @@
+using EssentialCSharp.Web.Extensions;
+
+namespace EssentialCSharp.Web.Services;
+
+public sealed class GuidelinesService : IGuidelinesService
+{
+    private readonly IReadOnlyList<GuidelineListing> _guidelines;
+
+    public GuidelinesService(IWebHostEnvironment environment, ILogger<GuidelinesService> logger)
+    {
+        FileInfo fileInfo = new(Path.Join(environment.ContentRootPath, "Guidelines", "guidelines.json"));
+        _guidelines = fileInfo.ReadGuidelineJsonFromInputDirectory(logger) ?? [];
+    }
+
+    public IReadOnlyList<GuidelineListing> Guidelines => _guidelines;
+}

EssentialCSharp.Web/Services/IGuidelinesService.cs

@@ -0,0 +1,6 @@
+namespace EssentialCSharp.Web.Services;
+
+public interface IGuidelinesService
+{
+    IReadOnlyList<GuidelineListing> Guidelines { get; }
+}