If function calling is sync, is MCP its async counterpart? Is that the gist of what MCP is? Open API (aka swagger) based function calling is standard already f

If function calling is sync, is MCP its async counterpart? Is that the gist of what MCP is? Open API (aka swagger) based function calling is standard already for sync calls, and it solves the NxM problem. I'm wondering if the proposed value is that MCP is async.