While Claude Opus 5.5 is facing controversy over perceived performance degradation shortly after its release, this is likely due to a conflict between the AI's new communication methods and existing program designs.
Imagine this: your AI assistant, which is usually so brilliant that it effortlessly handles complex coding problems, suddenly stops working mid-task one day, or starts providing responses that are shorter and less helpful than usual. It is as if a friend who was a genius just days ago has suddenly lost their memory.
Recently, on tech communities like Hacker News and social media, similar complaints have been pouring in regarding the latest model announced by Anthropic on September 22, 2026: ‘Claude Opus 5.5’. Ref 1, Ref 10, Ref 11
Why does this controversy matter?
AI is no longer just a toy; it has become a core tool for practical work. While controversies over performance degradation might just be a matter of perception, actual changes in the behavior of the AI you are using are directly linked to work efficiency. Reports that responses are becoming shorter or that instructions are not being followed properly demonstrate how sensitively users are watching the consistency and reliability of models as AI becomes deeply integrated into our lives. Ref 10
It’s smarter, so why does it look dumb?
Experts point to the ‘new personality’ of Opus 5.5 as one of the causes.
Put simply, if existing AI models were ‘taciturn students’ who only gave the correct answer when asked a question, Opus 5.5 has transformed into a ‘friendly tutor’ that keeps explaining, “I am currently on step 1,” and “Now moving on to step 2,” while solving problems. Ref 3, Ref 12
As the model was designed to be more communicative, it began reporting intermediate steps as progress updates. This creates a problem. Existing programs (applications) that utilize AI were designed with the expectation that the AI would deliver only the final result without saying anything. However, as the AI suddenly started talking more, programs began to mistake this for a signal that the task was finished or became confused. In other words, it is not that the AI itself has become dumber, but a ‘mismatch’ has occurred where the AI’s changed communication style conflicts with existing program logic. Ref 12
Has its performance really dropped?
Of course, not all complaints are due to these differences in communication style. If you look at actual real-world testers or benchmark tracking data, there is certainly feedback that responses are shorter or coding results are somewhat less sophisticated compared to the previous model. Ref 10
However, strictly looking at technical figures, Opus 5.5 is undeniably powerful. Compared to the previous model, Opus 5, its operating speed has improved by 30%, and the cost per token is 40% cheaper. Experts evaluate that this model remains one of the most powerful tools on the market for performing complex reasoning or coding tasks. Ref 5, Ref 11
How should we respond?
Anthropic seems aware that this controversy is a temporary phenomenon caused by technical changes. The developer community is now sharing practical ‘usage tips’, such as just saying “Continue” when the AI stops mid-task, which allows it to resume its work. Ref 12
As AI models themselves evolve, we also need to adjust the way we use AI (how we write prompts) little by little. Through their blog, Anthropic suggests methods such as explicitly specifying “rules for when to ask questions versus when to continue tasks” in configuration files like CLAUDE.md to prevent the AI from stopping work on its own. Ref 3
AI’s Perspective
When a smart AI suddenly appears to have turned clumsy, we must first look for a ‘change in communication language’ rather than a regression in technology. The language between AI and humans is evolving at this very moment, and sometimes the pace of that change outstrips the development of the tools we use. Ultimately, if we learn how to better understand and ‘tame’ AI, Opus 5.5 will become a more efficient assistant than ever before.
References
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[VueHN2.0 HasOpus5.5gottendumberfor anyone else in the last…](https://vue-hackernews-ssr-5cavbdjcta-ew.a.run.app/item/50238759) -
[ClaudeOpus5.5- API Pricing & Benchmarks OpenRouter](https://openrouter.ai/anthropic/claude-opus-5.5) - Getting the most out ofOpus5.5in Claude and… / claude.dev Blog
- ClaudeOpus5.5· Free AI Chatbot
- ClaudeOpus5.5: Specs, Price, Differences fromOpus5and Fable…
- Peter Yang built his own ride withOpus5.5: 30… - vibecoding.ru
- A Week After Launch, Paying Users Say Opus 5.5 Got Worse …
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[Opus 5.5 may be getting quietly worse · 58 HN comments Zeli](https://zeli.app/story/49901736) - Why Opus 5 Feels Worse: RLVR Theory Explained (2026 …
- Has Claude Opus 5.5 Actually Been Nerfed? What the Last Three …
- Claude Opus 5.5 Released — Performance Viewed Through Token Cost Reductions and Benchmark Metrics …
- Opus 5.5 Ditches Work Halfway? Official Reveal: Your Program …
- Claude’s Game Recompilation Capabilities May Have Been Nerfed
- The model itself has become dumber than before
- A mismatch between the new communication method and existing application logic
- Intentional performance reduction to cut server costs
- Intelligence level increased tenfold
- Operating speed improved by 30% and costs reduced by 40%
- Introduction of entirely new image editing features
- Delete and reinstall the model immediately
- Input additional commands such as 'Continue'
- Reset the model's settings