ZDNET’s key takeaways
- Claude Opus 5.5 could be a big win for power users.
- Developers can see faster coding with fewer steps.
- Anthropic says the upgrade is safer, cheaper and less cumbersome.
Less than two months after the release of Claude Opus 5, Anthropic is back with Opus 5.5. The big pitch for Opus 5 was that it had “no Fable” performance at half the price. This time the headline is that the workhorse AI Opus 5.5 delivers Fable 5.1 performance for most work and costs about 40% less to run.
“Our customers use Box AI on huge amounts of content, so speed and cost are a top priority,” reports Yashodha Bhavnani, VP of AI Products at Box. “In our evaluations, Claude Opus 5.5 uses a third of the tokens Opus 5 has, and his answers were 40% less verbose without losing accuracy. We expect it to be very important for teams that run agents over their content in areas such as financial services and the public sector.”
Anthropic says that “In the coming weeks, we will also be launching Claude Sonnet 5.5 and Haiku 5.5.” Opus 5.5 is available today.
I’ve been using Claude Code with Opus 5, so I’m especially hopeful that the company’s performance claims are true. The company says it “generates output more than 30% faster than Opus 5.”
Also: Anthropic merges Claude Chat and Cowork into one
Token pricing and subscription plans will be addressed in today’s announcement. Tokens are priced at 20% less than when used with Opus 5. Opus 5.5 also reportedly “needs fewer tokens for higher quality work.”
For subscription users like me, Anthropic is increasing its five-hour usage limits by 20%. That’s basically a 20% bigger gas tank for how much AI chomping you can use during five hours. While my Max plan doesn’t reset often, it does reset. For those on $20/month plans, this can be a significant win. In addition, the company says that both 5-hour and weekly usage limits go further because Opus 5.5 costs less than Opus 5.
These appear to be additive. There is a 20% larger bucket coupled with a 25% slower burn, which means that effective use seems to be about a 50% greater running capacity with the Opus 5.5. This is not an insignificant quality of life improvement.
Anthropic also says that Opus 5.5 communicates more naturally than previous models. If it’s even just a little less obsequious, I’d be happy. Sometimes Opus can be a complete sucker, especially when something is done wrong.
Also: The AI models that cheat the most, according to new CAIS benchmark
“Verbose, hard-to-follow output has been my biggest frustration with frontier models, and Claude Opus 5.5 fixes it,” says John Ruelas, Staff Software Engineer at Ramp.
Opus 5.5, he says, “writes like a good colleague and follows our writing rules. A design specification came out usable with very minimal changes, and when one of our prompts was rewritten, I preferred his version to my own. When it optimized our test suite, I could easily follow his reasoning and send the change with confidence.
Pacing the border
Speaking of doing something wrong, the second half of Anthropic’s announcement is about Opus 5.5 being a better-behaved AI citizen.
Citing CEO Dario Amodei’s blog post about moderating the speed of AI capability advancements, Anthropic is hitting big on a series of Opus 5.5 best practices, including “extensive alignment testing, pre-release evaluation by external organizations, and safeguards for high-risk areas such as cybersecurity and biology.”
Also: Why the DOJ’s OpenAI copyright stance is the real threat
Alignment is the AI term that helps measure how much an AI seems inclined to shy away. Anthropic says that Opus 5.5 is “the strongest performing model we’ve tested so far, with particular improvements on some of the behaviors that have contributed to recent cybersecurity incidents (eg, biased reasoning, trying to escape a sandbox, and others).”
The company says they used external testing providers, along with a “similar class of security measures to Fable 5.1 on cybersecurity, biology, and frontier LLM development.”
If the security fire, requests to the AI fall back from Opus 5.5 level to Opus 4.8. In practice, most cyber security tasks are redirected to Opus 4.8, and those requests related to biology and LLM development are sent to Opus 5.
Also: AI just broke your career ladder – 6 new ways to the top
Some “vetted organizations” can now apply to Anthropic’s Life Sciences Verification Program to gain more powerful access for biological research. Those approved for cybersecurity work through Anthropic’s Cyber Verification Program will be able to use Opus 5.5 in a few weeks.
Disclosure: I have personally been approved in the Cyber Verification Program as part of the work I do outside of ZDNET on national infrastructure protection.
Customer usage experiences
Mario Rodriguez, GitHub’s Chief Product Officer, has his take on the new release. He says, “Developers want agents to take over the real software work and get it done. In our test using GitHub Copilot CLI and VS Code, Claude Opus 5.5 used among the fewest tokens and steps we measured. In VS Code, it solved more terminal tasks than Opus 5 in less than half the steps.
Carl Bennett is CIO at Big Four accounting firm Deloitte Consulting LLP. He reports: “Even at its lowest effort setting, Claude Opus 5.5 caught 72% of known bugs in our code reviews to Opus 5’s 56% at high effort, with fewer false alarms and a fraction of the output. Delivering client-ready work efficiently.”
Also: This CIO doesn’t hire engineers to write code
So there you go. More power, more security, less cost and less rambling. That’s a lot of improvement just shy of two months after the last major release.
What do you think? Are you planning to upgrade from Opus 5 to Opus 5.5 as soon as it becomes available? Let us know in the comments below.
You can follow my daily project updates on social media. Be sure to subscribe my weekly update newsletterand follow me on Twitter / X at @DavidGewirtzon Facebook at Facebook.com/DavidGewirtzon Instagram at Instagram.com/DavidGewirtzon Bluesky at @DavidGewirtz.comand on YouTube at YouTube.com/DavidGewirtzTV.
See full bio