| layout | default |
|---|---|
| title | Chapter 3: ASP.NET Core HTTP Transport and Session Routing |
| nav_order | 3 |
| parent | MCP C# SDK Tutorial |
Welcome to Chapter 3: ASP.NET Core HTTP Transport and Session Routing. In this part of MCP C# SDK Tutorial: Production MCP in .NET with Hosting, ASP.NET Core, and Task Workflows, you will build an intuitive mental model first, then move into concrete implementation details and practical production tradeoffs.
HTTP deployment patterns in C# should be explicit about route scoping and per-session behavior.
- deploy MCP endpoints with ASP.NET Core integration
- design per-route/per-session tool availability safely
- avoid overexposing tool catalogs across endpoint surfaces
- align HTTP topology with policy and tenant boundaries
- expose focused MCP routes for distinct tool domains when possible
- keep all-tools endpoints gated and monitored
- use route-aware filtering for session-specific tool narrowing
- document endpoint semantics so clients can discover expected capability scope
You now have an HTTP architecture model for route-scoped MCP services in ASP.NET Core.
Next: Chapter 4: Tools, Prompts, Resources, and Filter Pipelines
The ParameterInfo interface in src/ModelContextProtocol.Analyzers/XmlToDescriptionGenerator.cs handles a key part of this chapter's functionality:
// Extract parameters
var parameterSyntaxList = methodDeclaration.ParameterList.Parameters;
ParameterInfo[] parameters = new ParameterInfo[methodSymbol.Parameters.Length];
for (int i = 0; i < methodSymbol.Parameters.Length; i++)
{
var param = methodSymbol.Parameters[i];
var paramSyntax = i < parameterSyntaxList.Count ? parameterSyntaxList[i] : null;
parameters[i] = new ParameterInfo(
ParameterType: param.Type.ToDisplayString(s_fullyQualifiedFormatWithNullability),
Name: param.Name,
HasDescriptionAttribute: descriptionAttribute is not null && HasAttribute(param, descriptionAttribute),
XmlDescription: xmlDocs?.Parameters.TryGetValue(param.Name, out var pd) == true && !string.IsNullOrWhiteSpace(pd) ? pd : null,
DefaultValue: paramSyntax?.Default?.ToFullString().Trim());
}
return new MethodToGenerate(
NeedsGeneration: true,
TypeInfo: ExtractTypeInfo(methodSymbol.ContainingType),
Modifiers: modifiersStr,
ReturnType: returnType,
MethodName: methodName,
Parameters: new EquatableArray<ParameterInfo>(parameters),
MethodDescription: needsMethodDescription ? xmlDocs?.MethodDescription : null,
ReturnDescription: needsReturnDescription ? xmlDocs?.Returns : null,
Diagnostics: diagnostics);
}
/// <summary>Checks if XML documentation would generate any Description attributes for a method.</summary>
private static bool HasGeneratableContent(XmlDocumentation xmlDocs, IMethodSymbol methodSymbol, INamedTypeSymbol descriptionAttribute)
{
if (!string.IsNullOrWhiteSpace(xmlDocs.MethodDescription) && !HasAttribute(methodSymbol, descriptionAttribute))This interface is important because it defines how MCP C# SDK Tutorial: Production MCP in .NET with Hosting, ASP.NET Core, and Task Workflows implements the patterns covered in this chapter.
The TypeInfo interface in src/ModelContextProtocol.Analyzers/XmlToDescriptionGenerator.cs handles a key part of this chapter's functionality:
return new MethodToGenerate(
NeedsGeneration: true,
TypeInfo: ExtractTypeInfo(methodSymbol.ContainingType),
Modifiers: modifiersStr,
ReturnType: returnType,
MethodName: methodName,
Parameters: new EquatableArray<ParameterInfo>(parameters),
MethodDescription: needsMethodDescription ? xmlDocs?.MethodDescription : null,
ReturnDescription: needsReturnDescription ? xmlDocs?.Returns : null,
Diagnostics: diagnostics);
}
/// <summary>Checks if XML documentation would generate any Description attributes for a method.</summary>
private static bool HasGeneratableContent(XmlDocumentation xmlDocs, IMethodSymbol methodSymbol, INamedTypeSymbol descriptionAttribute)
{
if (!string.IsNullOrWhiteSpace(xmlDocs.MethodDescription) && !HasAttribute(methodSymbol, descriptionAttribute))
{
return true;
}
if (!string.IsNullOrWhiteSpace(xmlDocs.Returns) &&
methodSymbol.GetReturnTypeAttributes().All(attr => !SymbolEqualityComparer.Default.Equals(attr.AttributeClass, descriptionAttribute)))
{
return true;
}
foreach (var param in methodSymbol.Parameters)
{
if (!HasAttribute(param, descriptionAttribute) &&
xmlDocs.Parameters.TryGetValue(param.Name, out var paramDoc) &&
!string.IsNullOrWhiteSpace(paramDoc))
{This interface is important because it defines how MCP C# SDK Tutorial: Production MCP in .NET with Hosting, ASP.NET Core, and Task Workflows implements the patterns covered in this chapter.
The TypeDeclarationInfo interface in src/ModelContextProtocol.Analyzers/XmlToDescriptionGenerator.cs handles a key part of this chapter's functionality:
// Build list of nested types from innermost to outermost
var typesBuilder = ImmutableArray.CreateBuilder<TypeDeclarationInfo>();
for (var current = typeSymbol; current is not null; current = current.ContainingType)
{
var typeDecl = current.DeclaringSyntaxReferences.FirstOrDefault()?.GetSyntax() as TypeDeclarationSyntax;
string typeKeyword;
if (typeDecl is RecordDeclarationSyntax rds)
{
string classOrStruct = rds.ClassOrStructKeyword.ValueText;
if (string.IsNullOrEmpty(classOrStruct))
{
classOrStruct = "class";
}
typeKeyword = $"{typeDecl.Keyword.ValueText} {classOrStruct}";
}
else
{
typeKeyword = typeDecl?.Keyword.ValueText ?? "class";
}
typesBuilder.Add(new TypeDeclarationInfo(current.Name, typeKeyword));
}
// Reverse to get outermost first
typesBuilder.Reverse();
string ns = typeSymbol.ContainingNamespace.IsGlobalNamespace ? "" : typeSymbol.ContainingNamespace.ToDisplayString();
return new TypeInfo(ns, new EquatableArray<TypeDeclarationInfo>(typesBuilder.ToImmutable()));
}
private static (XmlDocumentation? Docs, bool HasInvalidXml) TryExtractXmlDocumentation(IMethodSymbol methodSymbol)This interface is important because it defines how MCP C# SDK Tutorial: Production MCP in .NET with Hosting, ASP.NET Core, and Task Workflows implements the patterns covered in this chapter.
The LocationInfo interface in src/ModelContextProtocol.Analyzers/XmlToDescriptionGenerator.cs handles a key part of this chapter's functionality:
/// causes issues when the generator returns cached data with locations from earlier compilations.
/// </remarks>
private readonly record struct LocationInfo(string FilePath, TextSpan TextSpan, LinePositionSpan LineSpan)
{
public static LocationInfo? FromLocation(Location? location) =>
location is null || !location.IsInSource ? null :
new LocationInfo(location.SourceTree?.FilePath ?? "", location.SourceSpan, location.GetLineSpan().Span);
public Location ToLocation() =>
Location.Create(FilePath, TextSpan, LineSpan);
}
/// <summary>Holds diagnostic information to be reported.</summary>
private readonly record struct DiagnosticInfo(string Id, LocationInfo? Location, string MethodName)
{
public static DiagnosticInfo Create(string id, Location? location, string methodName) =>
new(id, LocationInfo.FromLocation(location), methodName);
public object?[] MessageArgs => [MethodName];
}
/// <summary>Holds extracted XML documentation for a method (used only during extraction, not cached).</summary>
private sealed record XmlDocumentation(string MethodDescription, string Returns, Dictionary<string, string> Parameters);
}This interface is important because it defines how MCP C# SDK Tutorial: Production MCP in .NET with Hosting, ASP.NET Core, and Task Workflows implements the patterns covered in this chapter.
flowchart TD
A[ParameterInfo]
B[TypeInfo]
C[TypeDeclarationInfo]
D[LocationInfo]
A --> B
B --> C
C --> D