Anthropic Releases Two New Claude Models in One Week
Anthropic released Claude Opus 5.5 on September 22 and Claude Sonnet 5.5 on September 28, with lower prices and stronger results on tasks where AI operates a computer and browses the web.
These releases don't change how Claude picks or cites websites. They do make AI assistants that read websites and complete tasks for people more capable and cheaper to run, which raises the value of a website an AI can read easily.
What Anthropic announced
- Claude Opus 5.5 (September 22, 2026): Anthropic’s top model, which it says costs about 40% less to run than Opus 5 on typical workloads. Anthropic describes it as “a reliable and adept researcher.” It scored 81.8% on OSWorld 2.1, a test of how well AI can operate a computer.
- Claude Sonnet 5.5 (September 28, 2026): a faster, lower-cost model that scored 80.1% on the same computer-use test.
Anthropic also says Opus 5.5 matches or beats its predecessor at resisting “prompt injection,” meaning hidden instructions planted on web pages to trick an AI. That includes when the AI is browsing the web.
What this does and doesn’t change
Neither announcement describes changes to how Claude searches the web or which websites it cites. So there’s no new “Claude ranking factor” to chase.
The bigger trend is the one to watch. Each new model is better at doing tasks for people, like comparing options, reading websites and filling out forms, and cheaper to run. That means more of your website’s visitors may eventually be AI assistants gathering information for a customer, not the customer themselves.
What it means for small businesses
An AI assistant reading your site needs the same things a busy customer does: prices, hours, service areas and contact details written in plain text, not buried in images or PDFs. It also helps to have pages that load and work without a lot of pop-ups in the way.
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