Hmm, indeed, so maybe I could have all this as an MCP, so I can just easily pass any imaginable data manipulation inside it, and then also have it support calling other MCPs, all inside that one MCP, to avoid filling context with intermediate data..

Sounds a lot like a shell to me.

Go idea. We will call this new MCP “bash”. It will allow you to stream the output of one command to the input of another incrementally as the data is generated.