Comment by 0xbadcafebee

It is bizarre that Marco said MCP is hard to compose. It's like he doesn't understand how composability works.

Unix programs are said to be composable, in that you can combine them in different ways to get more complex and useful functionality. But the applications themselves are not composeable. They just take input, perform calculation, and return output. Each app has unique input and output, and none know about other apps. So how can they possibly work together?

Bash acts like a programming language, allowing you to write a new program on the fly. It is very lightweight, but gives enough functionality to do two things: 1) call arbitrary programs, 2) connect their inputs and outputs, 3) make decisions about how to do this to result in a novel solution. It uses Unix pipes to make writing the program easier, but actually it could work fine without pipes, reading/writing program input/output with files.

The important thing is bash is a "glue" program that ties together the other programs. Bash is what makes those programs composeable. That, and the Unix API (execve(), open(), read(), write(), close()) that allows making the call, passing input, reading output, in one standard way for all programs.

MCP is both the application to call, and the Unix API to call them. Your agent harness is bash. Codemode is certainly a neat/more efficient way to write the code, but it's not necessary. What's necessary is getting a very large library of programs, like Unix programs (find, cat, grep, sed, awk, tr, cut, sort, tail, head, etc) that each have powerful functionality. The more programs you have, the more your bash script can do to chain them together and get more powerful results.

LLMs only use Bash because they didn't yet have MCP and a large library of MCP programs. Bash is a stopgap solution. The future is MCP (or whatever replaxes it).