Developer corrects 8x token cost error for Claude Code subagents: 54k, not 436k

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A developer team at DEV Community published a correction after discovering their earlier estimate of ~436,000 tokens per Claude Code subagent spawn was roughly eight times too high. Re-measuring with a minimal 'do-nothing' probe agent revealed the true spawn cost is 54,154 tokens, covering the system prompt, tool schemas, and related context written once into the prompt cache. The original figure was inflated because their method summed all input tokens across multiple API requests, counting the same cached context repeatedly at face value rather than accounting for cheaper cache-read pricing. This error shifted their delegation break-even threshold from 200,000 tokens down to approximately 40,000–50,000 tokens, meaning files larger than that threshold should be delegated to a subagent rather than read inline. The team noted the mistake was not conservative but actively costly, as it caused larger files to stay in the parent context and silently increase costs on every subsequent request.

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