> In my uneducated experience MCP is nothing more than a really well structured prompt.

MCP isn't a prompt (though prompts are a resource an MCP server can provide). An MCP client that is also the direct LLM manager toolchain has to map the data from MCP servers tool/prompt/resource definition into the prompt, and it usually does so using prompt templates that are defined for each model, usually by the model provider. So the meaningful part of having a “really well-structured prompt” part isn't from MCP at all, just something that already exists that the MCP client leverages.