A step-by-step guide to building an HTTP-based MCP (Model Context Protocol) server using ASP.NET and the ModelContextProtocol.AspNetCore NuGet package. Covers project setup, registering the MCP server in Program.cs, creating tool classes with McpServerToolType and McpServerTool attributes, writing descriptive parameter annotations so AI clients can discover and invoke tools, and connecting the server to AI clients like GitHub Copilot or VS Code via a .mcp.json config file. Uses a product catalog search as a concrete example, showing how a natural language question gets translated into a tool call and back into a human-readable answer.