Anthropic today announced the launch of its latest AI model, Claude Opus 4.8. Anthropic claims the model is a "more effective collaborator" with improvements in agentic coding, multidisciplinary reasoning, agentic computer use, knowledge work, and agentic financial analysis.
Testers have found Opus 4.8 to be "more reliable and sharper in its judgement" when doing agentic tasks, and the model also made gains in honesty.
Early testers report that Opus 4.8 is more likely to flag uncertainties about its work and less likely to make unsupported claims. This is borne out in our evaluations, which show that Opus 4.8 is around four times less likely than its predecessor to allow flaws in code it has written to pass unremarked.
Alignment assessments suggest the model hits new highs on measures of prosocial traits like supporting user autonomy and acting in the user's best interest. Rates of misaligned behavior like deception are lower than Opus 4.7 and similar to the Claude Mythos Preview.
Anthropic benchmarks indicate Opus 4.8 scored a 69.2% on SWE-Bench Pro, outperforming GPT–5.5 and Gemini 3.1 Pro on the test and several other benchmarks, though GPT–5.5 leads on the terminal-coding benchmark.
Opus 4.8's fast mode also runs at 2.5x the speed, and it is now three times cheaper than prior models.
Along with Opus 4.8, Anthropic is adding new features to its product lineup.
- Dynamic workflows (research preview) - Claude can complete bigger tasks in Claude Code. It is able to plan work and run hundreds of parallel subagents in a single session. It is able to complete codebase-scale migrations across hundreds of thousands of lines of code. The feature is available for Claude Code for Enterprise, Team, and Max plans.
- Effort control - In Claude.ai and Cowork, users can choose how much effort Claude puts into a response. With a lower setting, Claude will respond faster and use up rate limits more slowly. Opus 4.8 defaults to high effort, which Anthropic says is the best balance of quality and user experience.
- Messages API - The Messages API accepts system entries inside the messages array, so developers can update Claude's instructions mid-task.
Claude Opus 4.8 is available everywhere today. Pricing for regular use has not changed compared to Opus 4.7.
Anthropic is working on models that have the same capabilities as Opus 4.8 at a lower cost, and a new class of model that's even more intelligent than Opus. Anthropic says it has been developing safeguards for the Claude Mythos model it is testing with a small number of organizations, and it expects to be able to bring Mythos-class models to all customers "in the coming weeks."
