Claude Fable 5.1

proprietary

For demanding reasoning and long-horizon agentic work

Intelligence
Reasoning
Context
1M
Max output
128K
Input price
$10/1M tokens
Output price
$50/1M tokens

Capabilities

Reasoning & Interaction
Reasoning
Tool Calling
Output Control
Structured Output
JSON Mode
Infrastructure
Streaming
Batch Processing

Details

Model IDclaude-fable-5-1
Provider Anthropic
Creator anthropic
Familyclaude-fable
Licenseproprietary
Statusactive
Typechat
Input modalitiestext, image
Output modalitiestext
Open weightNo
Parameters—
Architecture—
Context window1M tokens
Max input—
Max output128K tokens
Reasoning tokens—
Thinking modesAdaptive
Knowledge cutoff
Training data cutoff
Release date
Retirement date
Priority tierYes
AWS Bedrock IDanthropic.claude-fable-5-1
GCP Vertex IDclaude-fable-5-1
Sourceofficial

Tools

Function Callingfunction_calling
Call external functions and APIs
Computer Usecomputer_use
Control a virtual desktop
MCPmcp
Connect to Model Context Protocol servers

Endpoints

MessagesPOST
Create messages with multi-turn conversationshttps://api.anthropic.com/v1/messages

Pricing

Input
$10
Output
$50
Cache write (5m)
$12.5
Cache write (1h)
$20
Cache read
$0.25
Batch in
$5
Batch out
$25

Family Comparison: claude-fable

ModelContextMax outPricing
Claude Fable 5.11M128K$10$50
Claude Fable 51M128K$10$50

API

GET/v1/models/anthropic/claude-fable-5-1

Claude Fable 5.1

claude-fable-5-1

For demanding reasoning and long-horizon agentic work

Changes · 3 entries
claude-fable-5-1createca7a400Nov 2, 2026, 03:02 AM
claude-fable-5-1update70e2981Sep 24, 2026, 11:29 AM
tools["function_calling"]→["function_calling","computer_use","mcp"]
descriptionFor demanding reasoning and long-horizon agentic work
statusactive
release_date2026-09-01
knowledge_cutoff2026-06
context_window1000000
max_output_tokens128000
performance5
reasoning5
training_data_cutoff2026-06
taglineFor demanding reasoning and long-horizon agentic work
thinking_modes["adaptive"]
bedrock_idanthropic.claude-fable-5-1
vertex_idclaude-fable-5-1
priority_tieryes
claude-fable-5-1create77b8547Sep 2, 2026, 06:42 AM