Anthropic released Claude Opus 5.5 on 22 September, the first model in its 5.5 family. It says the model costs 40% less to run than Opus 5 on typical work and writes its answers more than 30% faster. Sonnet 5.5 followed on 28 September.
The part that matters for marketing: Anthropic says it writes more clearly, puts key information first and follows the user's writing rules. One early tester said "it writes the way I do." That only works as well as the rules you give it.
This is why we build every brand a B.R.A.I.N.™ A better model with no brand knowledge writes better generic copy. A better model with your voice, your customer and your reasons to buy writes like you. Opus 5.5 also handles longer agent work and checks its own output, which helps when one brief feeds a whole campaign.