I've done stuff very much like the above with just regular tool calls through the various LLM APIs, but there are tons of disparate frameworks for how to harness up a tool, how they execute, how they are discovered, etc. None of it is rocket science.
But the nice thing about having a standard is that it's a well-lit path, but more importantly in the corporate workflow context is that it allows tools to be composed together really easily - often without any coding at all.
An analyst who has zero coding experience can type in a prompt, click "add" on some MCP tools, and stand up a whole workflow in a minute or two.
That's pretty cool.
And yeah, none of it is impossible to implement yourself (nor even very hard!) but standardization has a value in and of itself in terms of lowering barriers to entry.