Building an Azure Cosmos DB MCP Server with .NET 9 and Blazor The Model Context Protocol (MCP) is an open standard that lets Large Language Models (LLMs) such as Claude, ChatGPT, and GitHub Copilot interact with external systems through a well-defined tool interface. In this article, we will build a complete solution that exposes Azure Cosmos DB operations as MCP tools, and a Blazor Server client that can discover and invoke those tools through a browser-based UI. By the end of this article you will have: An ASP.NET Core MCP Server that wraps Azure Cosmos DB CRUD operations as callable MCP tools A Blazor Server Client that connects to the MCP Server, lists available tools, and lets you invoke them interactively A clear understanding of MCP architecture, tool registration, service design, and error handling Architecture Overview The solution consists of two projects. The CosmosDbMcpServer (ASP.NET Core Web API) hosts the MCP endpoint and talks to Azure Cos...