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AnthropicChatclaude-fable-5-1

Claude Fable 5.1

Anthropic's most intelligent model, for the hardest problems.

Fable 5.1 is Anthropic's most capable model, extending Fable 5 with stronger agentic coding, multistep research, and document work — for the tasks that run long and still have to come out right.

  • Agentic coding
  • Multistep research
  • Document work
Get your API keyTry in playgroundCompare models

Model details

Context window
1M tokens
Max output
128K tokens
Input
Text, images
Output
Text
Capabilities
Reasoning, Vision, Tool calling, Streaming
Interfaces
OpenAI-style Chat Completions, Anthropic-style Messages, OpenAI-style Responses

Pricing

Prices use the units shown below. No gateway fees. Usage, size and model options may affect the total.

Claude Fable 5.1 pricing.
MetricPrice
/ 1M input tokens$10
/ 1M output tokens$50
/ 1M cached input tokens$0.25
/ 1M cache write tokens (5 min)$12.5
/ 1M cache write tokens (1 hour)$20

Why teams pick it

  • Anthropic's most capable model for reasoning and agentic work
  • Stronger agentic coding and multistep research than Fable 5
  • 1M-token context for whole-repo and long-document work

Call Claude Fable 5.1

Claude Fable 5.1 answers on any of the APIs below — pick the one your code already speaks and just swap in your Cloakray key.

/v1/chat/completionsOpenAI-style Chat Completions · openai SDK or plain HTTP
curl https://api.cloakray.com/v1/chat/completions \
  -H "Authorization: Bearer ckr_..." \
  -H "Content-Type: application/json" \
  -d '{
  "model": "claude-fable-5-1",
  "messages": [
    {
      "role": "user",
      "content": "Hello"
    }
  ]
}'
/v1/messagesAnthropic-style Messages · @anthropic-ai/sdk SDK or plain HTTP
curl https://api.cloakray.com/v1/messages \
  -H "Authorization: Bearer ckr_..." \
  -H "Content-Type: application/json" \
  -d '{
  "model": "claude-fable-5-1",
  "max_tokens": 1024,
  "messages": [
    {
      "role": "user",
      "content": "Hello"
    }
  ]
}'
/v1/responsesOpenAI-style Responses · openai SDK or plain HTTP
curl https://api.cloakray.com/v1/responses \
  -H "Authorization: Bearer ckr_..." \
  -H "Content-Type: application/json" \
  -d '{
  "model": "claude-fable-5-1",
  "input": "Hello"
}'

Conversation compaction is also available at POST /v1/responses/compact.

More from Anthropic

Claude Opus 5.5Long-running agentic coding at a lower price than Opus 5.$4 / 1M input tokens · $20 / 1M output tokens · See all rates on the model pageClaude Fable 5Next-generation intelligence for knowledge work and coding.$10 / 1M input tokens · $50 / 1M output tokens · See all rates on the model pageClaude Opus 5State-of-the-art agentic coding for enterprise work.$5 / 1M input tokens · $25 / 1M output tokens · See all rates on the model page