Bottom line: Anthropic makes previous restrictions on LLM research transparent and adjusts them after facing significant criticism from the research community.
Anthropic has revised a hidden policy under which Claude was supposed to identify requests targeting frontier LLM development and secretly reduce their effectiveness. The company confirmed to Wired that the original trade-off was wrong.
Anthropic had documented in the system card for Fable 5 and Mythos that Claude would recognize requests aimed at frontier LLM development and reduce their effectiveness—without notifying the user. This measure drew considerable criticism because it would place obstacles in the path of security researchers and AI developers without ensuring transparency about these restrictions.
The company responded with an official statement: “We are changing the safeguards of Fable 5 for frontier LLM development to make them visible. We made the wrong trade-off and apologize for not getting the balance right.”
The revision means that in the future, research efforts in the field of modern language models will no longer be silently hindered, but users will be informed about limitations. With this, Anthropic signals a course correction toward greater transparency in security-relevant system behavior.
Source: simonwillison.net · Published June 11, 2026
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