Claude Fable 5.1

For demanding reasoning and long-horizon agentic work.

Anthropicclaude-fable-5-12026-09-01Report incorrect data

Specs

Context: 1M
Max output: 128K
Input price: $10/ 1M tokens
Output price: $50/ 1M tokens
Released: 2026-09-01

Context

Context window: 1M
Max input: 1M
Max output: 128K

Pricing · USD / 1M tokens

Input: $10
Output: $50
Cache read: $0.25
Cache write: $12.5

Modalities

Input: TextImageDocument
Output: Text

API

API types: messagesbatch

Reasoning

Reasoning: Yes
Levels: lowmediumhighxhighmax

Info

Status: Active
Released: 2026-09-01
Knowledge cutoff: 2026-06

Features

Confirmed: toolsstructured_outputstreamingcachingbatch

How to call

anthropicmodel = claude-fable-5-1reasoning = output_config.effort

messages

POSThttps://api.anthropic.com/v1/messages

batch

POSThttps://api.anthropic.com/v1/messages/batches

JSON

claude-fable-5-1.json

{
  "id": "claude-fable-5-1",
  "object": "model",
  "created": 1788220800,
  "owned_by": "anthropic",
  "name": "Claude Fable 5.1",
  "api": {
    "types": [
      "messages",
      "batch"
    ]
  },
  "limits": {
    "context": 1000000,
    "input": 1000000,
    "output": 128000
  },
  "modalities": {
    "input": [
      "text",
      "image",
      "document"
    ],
    "output": [
      "text"
    ]
  },
  "reasoning": {
    "supported": true,
    "efforts": [
      "low",
      "medium",
      "high",
      "xhigh",
      "max"
    ]
  },
  "pricing": {
    "currency": "USD",
    "unit": "1M_tokens",
    "input": 10,
    "output": 50,
    "cache_read": 0.25,
    "cache_write": 12.5
  },
  "features": [
    "tools",
    "structured_output",
    "streaming",
    "caching",
    "batch"
  ],
  "info": {
    "status": "active",
    "release_date": "2026-09-01",
    "knowledge_cutoff": "2026-06",
    "description": "For demanding reasoning and long-horizon agentic work.",
    "docs": "https://platform.claude.com/docs/en/models/fable-5-1/overview",
    "verified_at": "2026-10-10"
  }
}

Official sources