From Sonnet to Fable 5: Mastered Claude Code Config, Cut Tokens 40%
Cut token usage 40% with Claude Code model config. Learn aliases, opusplan, Fable 5, effort levels, fallback chains, and the 1M context window.
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To be honest, I’ve been using Claude Code for over half a year. Before, I just stuck with /model sonnet for everything. Until one day I noticed that for the same task, a colleague’s token consumption was only about 60% of mine—that’s when I realized how deep the model configuration rabbit hole really is.
This article is the result of me thoroughly digging through Claude Code’s official model configuration docs, combined with my own hard-earned lessons from falling into pits. From model selection to effort tuning, from fallback chains to the 1M context window—I’ll cover it all in one go.
First, Understand Model Aliases: Stop Memorizing Version Numbers
Claude Code has an alias system, so you don’t need to remember inhuman names like claude-opus-5-20260315. Just use the aliases:
# Switch to Opus (strongest reasoning)
/model opus
# Switch to Sonnet (daily development)
/model sonnet
# Switch to Haiku (fast and cheap)
/model haiku
# Switch to Fable 5 (ultra-long tasks)
/model fableThese aliases automatically point to the latest versions—convenient. But there’s a pitfall to watch out for: alias resolution differs across platforms:
