Model Context Protocol in .NET: Building and Consuming Universal AI Tools

Introduction In Part 1 and Part 2 of this series, we explored Microsoft Agent Framework's core concepts and workflow orchestration. Now we tackle a crucial question: how do your agents interact with the outside world? Traditionally, each AI framework had its own way of defining tools. Semantic Kernel used KernelFunction , LangChain used @tool decorators, and so on. This created silos—tools built for one framework couldn't be used in another. Enter the Model Context Protocol (MCP) —an open standard that makes AI tools universal. Build a tool once, use it everywhere. What is MCP? Model Context Protocol is an open specification (developed by Anthropic and adopted across the industry) that standardizes how AI applications access tools and context. Think of it as HTTP for AI tools —a common language that any AI client can speak. The Core Ideas 1. Servers expose capabilities: MCP Server: "I can do these things" ├── Tools: Functions agents can call ├── Resources: Data agents can read └── Prom