An unconfirmed leak suggests Anthropic's Claude Fable 5.5 is being prepared on Azure, based on a LiteLLM pricing entry that points to an East US 2 endpoint
馃毃 Fable 5.5 appeared in Azure鈥檚 East US 2 model catalog with GenerallyAvailable status
Context
A Fable 5.5 release would be Anthropic's next frontier model, and early infrastructure clues often precede launches, though this one is far from confirmed.
This is an unconfirmed leak. The evidence is a commit to LiteLLM, an open source tool that tracks model prices, not a Microsoft or Anthropic announcement. Microsoft's public Foundry catalog still lists Claude Fable 5.1 as the newest Fable model, and Anthropic has not commented.
Deep dive
On October 13, Alex Getman posted that Fable 5.5 appeared in Azure's East US 2 model catalog with GenerallyAvailable status, linking a LiteLLM commit.
The screenshot shows a new entry named azure_ai claude fable 5 5 in LiteLLM's model prices file, with a maximum of 1,000,000 input tokens and 128,000 output tokens, an input cost of $10 per million tokens, an output cost of $50 per million tokens and a deprecation date of December 5, 2027. Its source field points to an Azure management URL for models in the eastus2 region. The screenshot does not itself show a generally available status.
RuntimeWire reported that the LiteLLM entry is a credible infrastructure clue but does not establish that Anthropic has launched Fable 5.5, that Azure customers can call it, or that Microsoft marks it generally available. It noted that Microsoft's public documentation still lists Fable 5.1 as the newest Fable model. Crypto Briefing likewise reported that Anthropic has not confirmed the model.
Microsoft's Foundry documentation lists claude fable 5 1 and claude fable 5 as hosted on Anthropic infrastructure in preview. No Fable 5.5 page exists in the public catalog, so the prices in the LiteLLM entry should be treated as unverified.
What to expect next
Watch for an announcement from Anthropic or a Fable 5.5 page in Microsoft's Foundry catalog, either of which would confirm the leak.
Also watch whether the LiteLLM entry is kept or removed, whether the $10 and $50 per million token prices hold at launch, and whether the model appears on other clouds such as Amazon Bedrock or Google Vertex at the same time.