Claude Fable 5.1 API

Claude Fable 5.1 is a large language model by Anthropic, available on the Venice API as claude-fable-5-1. Requests are anonymized, so the provider never sees your identity.Claude Fable 5.1 improves on Claude Fable 5 across the board, with the biggest gains in agentic coding, long-running agentic workflows, and knowledge work such as long code refactors, front-end development, and finance and analysis tasks. It features a 1M token context window, 128K max output tokens, always-on adaptive thinking, and strong multimodal capabilities, and tends to be more concise in its plans and summaries.

Claude Fable 5.1 API pricing

Model ID	Variant	Privacy	Price
`claude-fable-5-1`	Standard	Anonymized	$12.00 input /$ 60.00 output per 1M tokens

Claude Fable 5.1 specifications

Spec	Value
Provider	Anthropic
Released	Aug 29, 2026
Privacy	Anonymized
Context window	1M tokens
Max output	125K tokens
Reasoning effort	low, medium, high, xhigh, max

How to use the Claude Fable 5.1 API

Send requests to POST https://api.venice.ai/api/v1/chat/completions with "model": "claude-fable-5-1" and your API key.

curl https://api.venice.ai/api/v1/chat/completions \
  -H "Authorization: Bearer $VENICE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-fable-5-1",
    "messages": [{ "role": "user", "content": "Explain TEE attestation in two sentences." }],
    "reasoning_effort": "high"
  }'