Shopify CEO Tobi: MCP vs CLI Debate Is at the Wrong Layer—Persistent-State REPLs Are the Key
_AustinCalvert_ · x · 2026-09-21
Shopify CEO Tobi Lütke argues the MCP vs CLI debate for LLMs happens at the wrong abstraction layer. Both work incredibly well as long as they run through a REPL-like environment that persists state. CLI often wins only because CLI tools are accessed via Bash, which is itself a REPL with persistent state (the file system)—not an intrinsic property of MCP, just a sign we need better harnesses.
He lists the current best REPLs: bash + fs, Jupyter kernels, and codemode-type REPLs (usually QuickJS). He adds that LLMs understand the concept of forward-evolving a system to solve a need very well.
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