Addy Osmani's guide to picking a Claude model: start with Opus at medium effort
bibryam · x · 2026-11-12
Addy Osmani published a playbook on choosing among Claude's four GA models (Haiku 5.5, Sonnet 5.5, Opus 5.5, Fable 5.2).
Key advice:
- Start most work on Opus 5.5 at medium effort: it's the Claude Code default and costs half as much per token as Fable 5.2.
- Adjust effort before switching models.
- Sonnet 5.5 for well-scoped everyday work (bug fixes, spec-driven features), though migrations and performance optimizations may still warrant Opus or Fable.
- Haiku 5.5 for cheap, high-volume tasks like classification, routing, and extraction, and as subagents for larger models.
- Fable 5.2 for the hardest coding, finance, and research projects.
- Claude Mythos 5.2 remains available only via verification programs for cybersecurity and life sciences research.
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