mcp.extensions

A collection of reusable .NET middleware, attributes, and services to extend and enhance ASP.NET Core applications working with the Model Context Protocol.

Built against ModelContextProtocol SDK v0.4.0-preview.3.

Features

• Audience-Based Segmentation 🎯

  • McpAudienceAttribute: Declarative attribute for audience-based access control on MCP tools, resources, and prompts
  • Streaming Middleware: Real-time filtering of MCP responses based on client audience credentials
    • StreamingToolFilteringMiddleware: Filters tools in real-time based on audience
    • StreamingResourceFilteringMiddleware: Filters resources in real-time based on audience
    • StreamingPromptFilteringMiddleware: Filters prompts in real-time based on audience
  • IAudienceFilterService: Unified service for managing audience-to-resource mappings
  • 📖 Complete Guide: Comprehensive documentation on audience segmentation and streaming implementation

• Logging Middleware

  • HeaderLoggingMiddleware: Logs HTTP request headers for diagnostics and auditing
  • RequestBodyLoggingMiddleware: Logs incoming HTTP request bodies for debugging and traceability
  • ResponseBodyLoggingMiddleware: Logs outgoing HTTP response bodies for monitoring and troubleshooting

• Legacy Services (Deprecated)

  • IToolAudienceService: Legacy interface for tool audience management (use IAudienceFilterService instead)

Getting Started

Quick Start: Audience-Based Segmentation

The easiest way to enable audience-based filtering for your MCP server:

// 1. Register services and scan your assembly for MCP attributes
builder.Services.AddMcpAudienceFiltering(Assembly.GetExecutingAssembly());

// 2. Apply all filtering middlewares
app.UseMcpAudienceFiltering();

// 3. Decorate your MCP tools, resources, and prompts with audience restrictions
public class MyMcpTools
{
    [McpServerTool("admin_tool")]
    [McpAudience("ADMIN")]
    public async Task<Result> AdminOnlyTool() { }
    
    [McpServerTool("public_tool")]
    [McpAudience("PUBLIC", "ADMIN")]
    public async Task<Result> PublicTool() { }
}

Clients send their audience type via the X-AGENT-MODE header:

GET /mcp/tools
X-AGENT-MODE: ADMIN

📖 For a complete guide with examples, best practices, and technical details, see the McpAudienceAttribute and Streaming Implementation Guide

Advanced Usage

Logging Middleware:

app.UseMiddleware<HeaderLoggingMiddleware>();
app.UseMiddleware<RequestBodyLoggingMiddleware>();
app.UseMiddleware<ResponseBodyLoggingMiddleware>();

Contributing

Contributions are welcome! Please open issues or submit pull requests for new features, bug fixes, or improvements.

License

MIT