Tobi Lütke: MCP vs CLI debate is at the wrong layer — what matters is a stateful REPL
arjunrajlab · x · 2026-09-21
Shopify CEO Tobi Lütke argues the MCP vs CLI debate is framed at the wrong layer: both work remarkably well as long as they run through a REPL-like environment that can persist state.
CLI tools typically run via BASH, which is itself a REPL with persistent state (the file system), which is why CLI performs better than MCP today — not an intrinsic flaw of MCP, just a signal that better harnesses are needed. He lists the best current options: bash + fs, Jupyter kernels, and codemode-style REPLs like QuickJS.
Thanks to agentic RL, LLMs understand evolving a system forward to solve a problem — mutating codebases, querying databases, then operating on results — but only with an execution environment backing them.
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