Claude Fable 5 API

Q: What is the Claude Fable 5 model ID?

Use anthropic/claude-fable-5 as the model parameter. Requests go to the OpenAI-compatible endpoint with your AI/ML API key.

Try this model

Claude Fable 5 is Anthropic's model designed for complex reasoning and agentic coding workflows. Features a 1M token context window, adaptive thinking, and strong performance across multilingual tasks, long-context handling, and vision.

Modalities: Text, ImageText
In / Out price: $10/$50per 1M
Context window: 1M tokens
Released: Jun 9, 2026

Claude Fable 5 overview

Claude Fable 5 by Anthropic

Claude Fable 5 is Anthropic's model designed for complex reasoning and agentic coding workflows.

Claude Fable 5 specs

Model ID: anthropic/claude-fable-5
Developer: Anthropic
Context window: 1,000,000 tokens
Max output: 128,000 tokens
Input: Text, Image
Output: Text
API: OpenAI-compatible, base URL https://api.aimlapi.com/v1

What Is Claude Fable 5 API?

Claude Fable 5 API is Anthropic’s latest large language model interface designed for developers, startups, enterprises, and AI product teams seeking advanced reasoning, long-context understanding, agentic workflows, and reliable production-scale deployments. Built on the newest generation of Claude architecture, Fable 5 expands beyond traditional chatbot interactions by providing a foundation for sophisticated AI applications that can analyze complex information, maintain context across lengthy conversations, execute multi-step tasks, and generate highly structured outputs.

Advanced Reasoning and Problem Solving

One of the defining strengths of Claude Fable 5 is its enhanced reasoning engine. The model can break down difficult problems into manageable components, evaluate multiple possibilities, identify dependencies, and generate well-supported conclusions.

For businesses, this means the model can assist with:

`Strategic Analysis`

Organizations can use Claude Fable 5 to evaluate market trends, analyze competitive landscapes, identify risks, and summarize large collections of research materials.

`Technical Decision Support`

Engineering teams can leverage the model for architecture planning, design reviews, troubleshooting workflows, and system documentation.

`Research Applications`

Researchers can process extensive documents, identify patterns, extract insights, and generate concise summaries from large information sources.

The result is a model capable of functioning as a highly effective analytical assistant rather than a simple text generator.

Large Context Window

Modern enterprises often work with substantial amounts of information. Traditional AI systems frequently struggle when documents become too large or conversations extend over many interactions.

Claude Fable 5 is designed to maintain coherence across extensive contexts, making it ideal for applications involving:

Legal Documents

Large contracts, policy libraries, compliance frameworks, and regulatory documentation can be processed more effectively.

Technical Documentation

Software documentation, system specifications, API references, and engineering reports can remain accessible within a single workflow.

Knowledge Bases

Organizations can integrate internal documentation, training materials, and operational procedures into AI-powered systems.

This expanded context handling significantly reduces the need for aggressive document chunking and complex retrieval strategies.

High-Performance Coding Assistance

Software development remains one of the most valuable use cases for modern AI models. Claude Fable 5 includes substantial improvements in code generation, debugging, refactoring, and software design support.

Code Generation

Developers can generate production-ready code across multiple programming languages, frameworks, and environments.

Bug Detection

The model can identify logical errors, implementation flaws, and edge cases that might otherwise be overlooked.

Refactoring Support

Legacy systems can be modernized through intelligent code restructuring while preserving functionality.

Documentation Creation

Claude Fable 5 can generate technical documentation, inline comments, API descriptions, and onboarding materials.

Reliable Data Formatting

Many enterprise applications require predictable outputs rather than free-form text. Claude Fable 5 excels at producing structured responses suitable for automation pipelines.

JSON: Ideal for API integrations and software workflows.
XML: Useful for legacy enterprise environments.
Markdown: Excellent for documentation systems and publishing workflows.
Tabular Data: Supports reporting, analytics, and business intelligence applications.

AI Customer Support

Organizations can deploy intelligent support systems capable of understanding customer issues, retrieving relevant information, and generating accurate responses. Benefits include faster response times, reduced support costs, and improved customer satisfaction.

Software Engineering Platforms

Developer-focused applications can leverage Claude Fable 5 for code generation, code review, debugging, testing assistance, and technical documentation.

Enterprise Knowledge Management

Companies often struggle to make internal information accessible. Claude Fable 5 can transform documentation repositories into intelligent knowledge systems that provide contextual answers and actionable insights.

Research and Analysis

Financial institutions, consulting firms, research organizations, and analysts can use the API to process large volumes of information and generate comprehensive summaries.

Content Operations

Marketing teams, publishers, and content organizations can automate research, drafting, editing, localization, and content optimization workflows.

AI Agents and Workflow Automation

Claude Fable 5 is particularly effective for systems that coordinate multiple tasks, tools, and decision points within a larger workflow.

Claude Fable 5 vs Previous Claude Generations

Compared with earlier Claude models, Fable 5 introduces improvements across several critical dimensions.

`Better Reasoning`

More consistent problem-solving and deeper analytical capabilities.

`Improved Long-Context Performance`

Enhanced ability to work with extensive documents and lengthy conversations.

`Stronger Agent Capabilities`

Better support for planning, task management, and tool orchestration.

`Enhanced Coding Performance`

More accurate code generation and debugging assistance.

Gr`eater Enterprise Readiness`

Expanded governance, security, and deployment controls.

Use cases

Claude Fable 5 is documented as suited to software engineering and coding, including ambitious coding projects, code review, performance work, and long-running development sessions. It is also suited to knowledge work, especially complex multi-stage work such as deep research, analysis, and enterprise workflows involving financial analysis, spreadsheets, slides, and documents.

It is documented for long-running, autonomous or agentic tasks, including work that can span hours, days, or multi-day projects with planning across stages, delegation to sub-agents, and self-verification. It is also suited to vision-heavy work, such as understanding diagrams, charts, and tables in files and PDFs, and checking outputs against the original design or goal.

Capabilities

Function calling
Streaming
Structured outputs
Reasoning
Web search

Claude Fable 5 benchmarks by Artificial Analysis

See how Claude Fable 5 compares in generation speed. Data retrieved Nov 3, 2026.

Speed#149 / 21968.2Output tokens / second Humanity's Last Exam#4 / 45855.5%Score GPQA Diamond#18 / 43992.6%Score Terminal-Bench 4.0#14 / 15442.4%Score

Speed

Output tokens / second

Benchmark results

Compare 8 models available on AI/ML API across 5 independent benchmarks.

Humanity's Last Exam

Expert-written questions across academic subjects.

Claude Fable 5 API pricing

Claude Fable 5 pricing in US dollars
Usage	Price	Unit
Input	$10	1M tokens
Output	$50	1M tokens
Cached input	$1	1M tokens

Prices from the AI/ML API price list, checked on Nov 4, 2026.

Claude Fable 5 vs other models: token prices

AI/ML API input and output rates for 5 models, per million tokens.

AI/ML API model prices in USD per million tokens
Model	Input	Output
Claude Fable 5	$10	$50
Claude Haiku 5.5	$0.1	$0.5
Claude Sonnet 5.5	$2	$10
Claude Opus 5.5	$4	$20
Claude Fable 5.1	$10	$50

How to use the Claude Fable 5 API

View docs

Build with your agent

Give your agent the model details, code and documentation.

1Get your API key

Create API key

export AIMLAPI_KEY="8f2b4c7d9a1e6b3f…"

2Make your first request

curl 'https://api.aimlapi.com/v1/chat/completions' \
  -H "Authorization: Bearer $AIMLAPI_KEY" \
  -H 'Content-Type: application/json' \
  -d '{
  "model": "anthropic/claude-fable-5",
  "messages": [
    {
      "role": "user",
      "content": "Write a haiku about the ocean."
    }
  ]
}'

import os
import requests

headers = {
    "Authorization": f"Bearer {os.environ['AIMLAPI_KEY']}",
    "Content-Type": "application/json",
}
payload = {
    "model": "anthropic/claude-fable-5",
    "messages": [
        {
            "role": "user",
            "content": "Write a haiku about the ocean."
        }
    ]
}

response = requests.post("https://api.aimlapi.com/v1/chat/completions", headers=headers, json=payload, timeout=120)
response.raise_for_status()
print(response.json())

const response = await fetch("https://api.aimlapi.com/v1/chat/completions", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.AIMLAPI_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    "model": "anthropic/claude-fable-5",
    "messages": [
      {
        "role": "user",
        "content": "Write a haiku about the ocean."
      }
    ]
  }),
});

if (!response.ok) throw new Error(`HTTP ${response.status}`);
console.log(await response.json());

All posts

Claude Fable 5 FAQ

How much does Claude Fable 5 cost?

Claude Fable 5 costs $10 input and $50 output per 1M tokens on AI/ML API, billed as you go with no subscription.

What is the Claude Fable 5 model ID?

Use anthropic/claude-fable-5 as the model parameter. Requests go to the OpenAI-compatible endpoint with your AI/ML API key.

What is the context window of Claude Fable 5?

Claude Fable 5 accepts up to 1,000,000 tokens of context and returns up to 128,000 output tokens.

Start building with Claude Fable 5

Get API key

Claude Fable 5 API

anthropic/claude-fable-5

Build with your agent

Give your agent the model details, code and documentation.

1Get your API key

Create API key

export AIMLAPI_KEY="8f2b4c7d9a1e6b3f…"

2Make your first request

curl 'https://api.aimlapi.com/v1/chat/completions' \
  -H "Authorization: Bearer $AIMLAPI_KEY" \
  -H 'Content-Type: application/json' \
  -d '{
  "model": "anthropic/claude-fable-5",
  "messages": [
    {
      "role": "user",
      "content": "Write a haiku about the ocean."
    }
  ]
}'

import os
import requests

headers = {
    "Authorization": f"Bearer {os.environ['AIMLAPI_KEY']}",
    "Content-Type": "application/json",
}
payload = {
    "model": "anthropic/claude-fable-5",
    "messages": [
        {
            "role": "user",
            "content": "Write a haiku about the ocean."
        }
    ]
}

response = requests.post("https://api.aimlapi.com/v1/chat/completions", headers=headers, json=payload, timeout=120)
response.raise_for_status()
print(response.json())

const response = await fetch("https://api.aimlapi.com/v1/chat/completions", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.AIMLAPI_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    "model": "anthropic/claude-fable-5",
    "messages": [
      {
        "role": "user",
        "content": "Write a haiku about the ocean."
      }
    ]
  }),
});

if (!response.ok) throw new Error(`HTTP ${response.status}`);
console.log(await response.json());

Docs for AI agents Plain-text index · llms.txt API documentation API reference and examples

Claude Fable 5 API

Claude Fable 5 overview

Claude Fable 5 by Anthropic

Claude Fable 5 specs

What Is Claude Fable 5 API?

Advanced Reasoning and Problem Solving

Strategic Analysis

Technical Decision Support

Research Applications

Large Context Window

Legal Documents

Technical Documentation

Knowledge Bases

High-Performance Coding Assistance

Code Generation

Bug Detection

Refactoring Support

Documentation Creation

Reliable Data Formatting

AI Customer Support

Software Engineering Platforms

Enterprise Knowledge Management

Research and Analysis

Content Operations

AI Agents and Workflow Automation

Claude Fable 5 vs Previous Claude Generations

Better Reasoning

Improved Long-Context Performance

Stronger Agent Capabilities

Enhanced Coding Performance

Greater Enterprise Readiness

Use cases

Capabilities

Speed

Benchmark results

Humanity's Last Exam

GPQA Diamond

Terminal-Bench 4.0

AA-LCR

SciCode

Claude Fable 5 API pricing

Claude Fable 5 vs other models: token prices

How to use the Claude Fable 5 API

Build with your agent

1Get your API key

2Make your first request

Models similar to Claude Fable 5

Claude Haiku 5.5

Claude Sonnet 5.5

Claude Opus 5.5

GPT-6 Astra

GPT-5 Image

GPT-5.4 Image 2

Related articles

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Best LLMs for Long-Context & Multimodal Tasks in 2026

Claude Fable 5 FAQ

Start building with Claude Fable 5

`Strategic Analysis`

`Technical Decision Support`

`Research Applications`

`Better Reasoning`

`Improved Long-Context Performance`

`Stronger Agent Capabilities`

`Enhanced Coding Performance`

Gr`eater Enterprise Readiness`