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Anthropic: Claude Fable 5.1

Source description (English)

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: long code refactors, front-end and visual...

Overview

Model specifications

Context
1,000,000 tokens
Maximum output
128,000 tokens
Architecture
text+image+file->text
Tokenizer
Claude
Knowledge cutoff
Not provided
Moderated
Yes
OPENROUTER

Complete pricing

Synchronized OpenRouter rates. Token prices are shown per one million tokens.

Input
$10
per 1M tokens
Output
$50
per 1M tokens
Cache read
$0.25
per 1M tokens
Cache write
$12.5
per 1M tokens
Cache write (1h)
$20
per 1M tokens
API

Model configuration

Reasoning

Reasoning required
Yes
Default parameters
high
Capabilities
max, xhigh, high, medium, low
API

Quick start

Set OPENROUTER_API_KEY locally. Python requires requests; JavaScript runs in Node.js. Keep the key on the server.

API documentation

curl --fail-with-body https://openrouter.ai/api/v1/chat/completions \
  -H "Authorization: Bearer $OPENROUTER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"anthropic/claude-fable-5.1","messages":[{"role":"user","content":"Hello!"}]}'
Capabilities

InputOutput

Input
textimagefile
Output
text
Reasoning

No · max · xhigh · high · medium · low

API

Supported API parameters

include_reasoningmax_completion_tokensmax_tokensreasoningreasoning_effortresponse_formatstopstructured_outputstoolsverbosity
Available providers

4 providers

Checked: September 7, 2026

Live providers on OpenRouter

Provider availability, latency, throughput and routing can change continuously. Open the source page for current operational data.

OpenRouter

Azure

Not provided
Context
1M
Maximum output
128K
Input
$10
Output
$50
Cache read
$0.25
Cache write
$12.5

Anthropic

Not provided
Context
1M
Maximum output
128K
Input
$10
Output
$50
Cache read
$0.25
Cache write
$12.5

Amazon Bedrock

Not provided
Context
1M
Maximum output
128K
Input
$10
Output
$50
Cache read
$0.25
Cache write
$12.5

Google

Not provided
Context
1M
Maximum output
128K
Input
$10
Output
$50
Cache read
$0.25
Cache write
$12.5
anthropic

4 models

All models