A guide to building production-ready AI agent platforms in the .NET ecosystem by combining three complementary technologies: .NET Aspire for distributed application orchestration and observability, Semantic Kernel for AI orchestration and plugin management, and Model Context Protocol (MCP) for standardized tool discovery and invocation. The architecture separates concerns so that ASP.NET Core handles HTTP endpoints, Semantic Kernel plans and routes AI requests, MCP exposes enterprise capabilities as tools, and Aspire ties everything together with service discovery and OpenTelemetry-based monitoring. The post covers end-to-end workflow, best practices (thin MCP endpoints, DI registration, structured JSON responses), common mistakes (direct DB access by LLMs, embedding business logic in plugins), testing strategies across all layers, performance optimization, and security recommendations including authentication, authorization, rate limiting, and audit logging.
