The token-compression tool with 60k stars may be saving less than it claims

RTK, a single Rust binary that compresses terminal output before it reaches a coding agent, has crossed 60,000 GitHub stars on a "1/10 the price" pitch. A widely shared critique from developer Przemek Mroczek argues the headline savings are mostly theatre.

The viral "60 to 90% savings" is the share of raw command-line output RTK strips, not a cut to your actual invoice. It leaves the real cost drivers untouched: deep file reads, repository context, system prompts and the model's own reasoning tokens. Worse, Mroczek notes, RTK sits in the synchronous path between agent and shell, and when it silently drops a line of a stack trace the agent has no idea the context was mangled.

The metric nobody publishes is task success rate. Saving 80% on a prompt is a net loss if the thinner context makes the agent hallucinate, fail the build and loop. Until the token graphs ship with SWE-bench style accuracy numbers, the savings story is only half told.