Anthropic releases Claude Opus 4.8 with cheaper fast mode and Claude Code “dynamic workflows”
Confirmed
The takeaway
Claude Opus 4.8 (claude-opus-4-8) launched on May 28, 2026 at the same $5/$25 price as Opus 4.7.
Status
- Claim
Confirmed
- Our reporting
- High confidence
- Importance
- 3 of 5
- Last verified
- 11 October 2026
Your AI and this story
- GPT-6 Astra28 days after its cutoff
- Claude Opus 5.5In its training data
- Gemini 4 Hydrogen58 days after its cutoff
- Grok 4.7In its training data
It is after the cutoff of GPT-6 Astra and Gemini 4 Hydrogen, and can be in the training data of Claude Opus 5.5 and Grok 4.7.
Key facts
- Released May 28, 2026; model id claude-opus-4-8; $5/$25 per 1M tokens; fast mode $10/$50
- Context 1M tokens on Claude API, Bedrock and Vertex AI (200K on Microsoft Foundry); 128K output
- Online-Mind2Web 84%; OSWorld-Verified 82.3% (Anthropic)
- Claude Code dynamic workflows (research preview) spawn hundreds of parallel subagents; effort slider added to claude.ai and Cowork
- ‘Ultracode’ (Claude Code v2.1.154, May 28, per Pilot Shell): a toggle on the /effort slider that makes Claude orchestrate dynamic workflows for substantive tasks; Anthropic’s docs call it ‘a Claude Code setting rather than a model effort level’.
--effort ultracode(or Agent SDK effortLevel ‘ultracode’) turns it on and sets effort to xhigh; the model effort ladder stays low/medium/high/xhigh/max. Uses many more tokens per request. Later popular in ‘Opus 5.5 ultracode’ demo videos - Opus 4.8 later served as fallback model for Fable 5 / Opus 5.5 cyber classifier blocks
What happened
Testers found Opus 4.8 “more reliable and sharper in its judgement” on agentic tasks and more likely to flag uncertainty instead of making unsupported claims. The same day Anthropic announced its $65B Series H. The accompanying Claude Code video promoted /goal and /remote-control for long-running work.
Why it matters
Opus 4.8 was the last Opus 4.x release and a bridge to the Mythos-class releases in June. It is still used as the fallback model inside Anthropic’s safeguard stack.
Sources
7 sources from 7 sites. Numbers match the chips in the text.
7 sources: 2 primary, 4 press, 1 reaction
Primary
- Claude Code docs: model configuration (effort levels and ultracode)code.claude.com, docs
- Introducing Claude Opus 4.8 (Anthropic)anthropic.com, official
Press
- Pilot Shell: Ultracode in Claude Code, effort setting explainedpilot-shell.com, press
- MacRumors: Opus 4.8 with gains in coding and honestymacrumors.com, press
- Axios: Anthropic releases new model, Opus 4.8axios.com, press
- 9to5Mac: Anthropic upgrades Claude with Opus 4.89to5mac.com, press
Reactions
- Simon Willison: Claude Opus 4.8 — a modest but tangible improvementsimonwillison.net, discussion
Changes
- Added the ultracode setting
- Filed
