Anthropic shipped Opus 5.5 on September 22, 2026 — same 1M context as [Opus 5](/posts/claude-opus-5-marketers/) and [Fable 5.1](/posts/claude-fable-5-1-marketers/), but $4/$20 instead of $5/$25, cache reads cut 60% to $0.20, and a writing-style fix that actually lands. The number that matters for marketers isn't a benchmark — it's that 60% cache-read cut. Four jobs Opus 5.5 earns from Opus 5 this week, three where Fable 5.1 or Opus 5 still wins, one routing principle that holds, and the four breaking API changes you need to patch before Monday.
Anthropic's Fable 5.1 shipped September 1 with the same $10/$50 sticker as GPT-6 Astra but a 75% cache-read cut and flat pricing across the full 1M window. That changes which agent loops become viable: persistent brand-context documents can stay open across hundreds of turns. Four jobs to give it, two to keep on Opus 5, and three API breaking changes marketers need to patch this week.
A Claude-powered Slack agent that handles campaign briefs, copy drafts, competitor checks, weekly recaps, and content ideas — replacing a strategist, copywriter, and analyst for the day-to-day.
Wire a Slack slash command to an n8n workflow that fans out to Perplexity for cited research, hands the result to Claude for a 3-paragraph rewrite, and posts it back into the same channel — full JSON, prompts, and the dispatch_failed trap included.
