Codex ships Code Mode: JS programs filter MCP data before it hits context
alex_frantic · x · 2026-09-18
OpenAI's Codex has shipped Code Mode: instead of the model calling MCP servers directly, it writes a small JavaScript program that calls and filters the data before it reaches the model's context.
The author previously inspected what MCPs actually dump into the context and was terrified — tens of thousands of tokens wasted. He had concluded that CLI + skills was a better idea, letting the model use the command line to filter and process data and chain things together.
Code Mode essentially productizes that idea. He also notes MCP has improved on auth, statelessness, and ecosystem support — "MCP good."
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