By Hannan Tariq
If you just want the quick answer, start with Claude Sonnet 5.5. It is the sensible all-rounder for most everyday writing. Think of it as the dependable family car: capable, quick and unlikely to demand a racetrack.
Use Opus 5.5 when the job is difficult, Haiku 5.5 when it is short and repetitive, and Fable 5.1 only when testing shows that you genuinely need the extra brainpower.
Sonnet 5.5: best starting point for most writing
Anthropic describes Sonnet 5.5 as suited to clear writing, quick changes and everyday jobs. That makes it the model to try first for:
- CV and cover-letter polishing
- Blog and article drafts
- Emails and marketing copy
- Social-media captions
For a CV, give it your real work history and the job advert. Tell it to improve the wording without inventing achievements. A made-up award may sound shiny, but recruiters tend to notice when your trophy cabinet exists only in cyberspace.
Opus 5.5: bring it in for tougher edits
Opus 5.5 is designed for more complex work. Try it when an article has many sources, a CV needs a major career-change rewrite, or your copy must follow a detailed brand voice.
That does not mean Opus automatically writes better. Paying for a bigger hammer does not make every nail more important.
Haiku 5.5: quick ideas without the fuss
Haiku 5.5 is Anthropic’s fastest current model and is aimed at high-volume work. It is worth trying for caption ideas, headlines, short rewrites and several versions of the same message.
What about Fable 5.1?
Fable is built for demanding, long jobs. For normal writing, it may be like hiring a crane to lift your pencil. Anthropic itself says most workloads should start with Opus before moving to Fable.
The easiest way to choose
Give two models the same instructions and facts. Hide their names, read both answers and ask:
- Did it follow the instructions?
- Did it keep the facts correct?
- Which answer needed less fixing?
Anthropic also recommends testing models on your real task. Our practical verdict: start with Sonnet, use Haiku for quick variations, and move to Opus only when the harder job earns it. No crown, no fan club—just the right tool for the page.
This article was created with the help of Sylar AI, our in-house AI assistant.