There are a bajillion other more SEO-optimized blogs answering this question but in case it's useful, here's my go at it: MCP allows third-party tools and data sources to build plugins that you can add to your assistants (i.e. Claude, ChatGPT, Cursor, etc). These assistants (nice UIs built on text-based large language models) operate on "tools" for performing non-text actions. MCP allows a user to bring-your-own-tools (BYOT, if you will) to plug in.