Fable 5 is back.
Claude@claudeai
93 views
Jul 02, 2026
~1 min read
Advertisement
1
Fable 5 is back.
2
Following conversations with the US government, we’ve updated our cybersecurity safeguards.
The vast majority of coding work is unaffected.
In the near term, the new safeguards will flag a slightly higher fraction of harmless requests than the previous Fable safeguards; we’re working to refine these over the coming weeks. Users will be clearly notified when a request is flagged, and they’ll instead receive a response from Opus 4.8.
Our biology and chemistry classifiers are unchanged from our initial launch. These are still broader than we would like; they trigger fallbacks to Opus 4.8 on basic biology-adjacent questions. Improvements to these classifiers are landing soon.
The vast majority of coding work is unaffected.
In the near term, the new safeguards will flag a slightly higher fraction of harmless requests than the previous Fable safeguards; we’re working to refine these over the coming weeks. Users will be clearly notified when a request is flagged, and they’ll instead receive a response from Opus 4.8.
Our biology and chemistry classifiers are unchanged from our initial launch. These are still broader than we would like; they trigger fallbacks to Opus 4.8 on basic biology-adjacent questions. Improvements to these classifiers are landing soon.
3
All paid plans with usage included can access Fable 5 through July 7. You can use Fable 5 up to 50% of your weekly usage limit, after which you can switch to another model for the remainder of your usage. You can also continue using Fable via usage credits.
More here: support.claude.com/en/articles/15…
More here: support.claude.com/en/articles/15…
4
If one of your requests is mistakenly flagged in Claude Code, run /feedback to file a report. On Claude.ai and Cowork, you can share feedback through the thumbs buttons.
This feedback helps us further tune these classifiers and reduce false positives over time.
This feedback helps us further tune these classifiers and reduce false positives over time.
5
Read the Fable 5 blog post here: anthropic.com/news/claude-fa…
