Claude Fable 5 (Adaptive Reasoning, Max Effort, Opus 4.8 Fallback)
Anthropic • text
Claude Fable 5 is a Mythos-class model from Anthropic, built for autonomous knowledge work and coding. It supports text, image, and file inputs with text output, with reasoning support and...
Specifications
Context Window
1.0M tokens
Input Price/1M
$10.00
Output Price/1M
$50.00
Parameters
—
Speed
71 tok/s
Latency (TTFT)
80.1s
Max Output
128K tokens
Benchmarks
Claude Fable 5 (Adaptive Reasoning, Max Effort, Opus 4.8 Fallback) results on the main AI model evaluation benchmarks. Higher scores indicate better performance.
Agentic
| Benchmark | Score | Maximum | Methodology |
|---|---|---|---|
| Terminal-Bench Hard | 63.0 | 100.0 | — |
Coding
| Benchmark | Score | Maximum | Methodology |
|---|---|---|---|
| LiveBench Coding | 78.6 | 100.0 | Contamination-free benchmark with objective ground-truth answers |
| AA Coding Index | 76.5 | 100.0 | Artificial Analysis official API |
| SciCode | 60.0 | 100.0 | — |
Data Analysis
| Benchmark | Score | Maximum | Methodology |
|---|---|---|---|
| LiveBench Data Analysis | 80.0 | 100.0 | Contamination-free benchmark with objective ground-truth answers |
Language
| Benchmark | Score | Maximum | Methodology |
|---|---|---|---|
| LiveBench Language | 88.5 | 100.0 | Contamination-free benchmark with objective ground-truth answers |
Long Context
| Benchmark | Score | Maximum | Methodology |
|---|---|---|---|
| AA-LCR | 70.0 | 100.0 | — |
Math
| Benchmark | Score | Maximum | Methodology |
|---|---|---|---|
| LiveBench Math | 93.9 | 100.0 | Contamination-free benchmark with objective ground-truth answers |
overall
| Benchmark | Score | Maximum | Methodology |
|---|---|---|---|
| LMArena Elo | 1508.0 | 2000.0 | Crowdsourced blind pairwise comparisons |
| LiveBench Global | 78.3 | 100.0 | Contamination-free benchmark with objective ground-truth answers |
| AA Intelligence Index | 59.9 | 100.0 | Artificial Analysis official API |
Reasoning
| Benchmark | Score | Maximum | Methodology |
|---|---|---|---|
| GPQA Diamond | 93.0 | 100.0 | Artificial Analysis official API |
| LiveBench Reasoning | 87.3 | 100.0 | Contamination-free benchmark with objective ground-truth answers |
| IFBench | 63.0 | 100.0 | — |
| HLE | 53.0 | 100.0 | — |
Tool Use
| Benchmark | Score | Maximum | Methodology |
|---|---|---|---|
| Tau²-Bench | 99.0 | 100.0 | — |
Information
- Release date
- June 09, 2026
- Tool Calling
- ✅ Supported
- Vision
- ✅ Supported
- Audio
- ❌ Not supported
Full Analysis: Claude Fable 5 (Adaptive Reasoning, Max Effort, Opus 4.8 Fallback)
What is Claude Fable 5 (Adaptive Reasoning, Max Effort, Opus 4.8 Fallback)?
Claude Fable 5 (Adaptive Reasoning, Max Effort, Opus 4.8 Fallback) is an AI model developed by Anthropic, classified as a text model. It focuses on text processing and natural language generation. As a proprietary model, it is available via Anthropic's cloud API. With a context window of 1.0M tokens, it is suitable for processing long documents such as contracts, books, and complete codebases.
Pricing & Costs in 2026
Claude Fable 5 (Adaptive Reasoning, Max Effort, Opus 4.8 Fallback) is usage-based, priced at $10/1M input tokens and $50/1M output tokens. For context: 1 million tokens is approximately 750,000 words, or about 10 average-length books. The premium pricing reflects the model's frontier capabilities, recommended for complex reasoning, analysis, and generation tasks where quality takes priority over cost.
Benchmarks & Performance
Claude Fable 5 (Adaptive Reasoning, Max Effort, Opus 4.8 Fallback) was evaluated on 16 different benchmarks, covering categories like Agentic, Coding, Data Analysis, Language, Long Context, Math, overall, Reasoning, Tool Use. Results show exceptional performance across available evaluations.
It's important to note that benchmarks measure specific aspects and don't capture the full user experience. Factors like instruction adherence, behavior in long conversations, and real-world task quality vary significantly between models and aren't always reflected in standard scores.
Recommended Use Cases
Claude Fable 5 (Adaptive Reasoning, Max Effort, Opus 4.8 Fallback) specializes in text, offering advanced capabilities for creating and processing text content.
Comparison with Alternatives
In the 2026 AI model ecosystem, Claude Fable 5 (Adaptive Reasoning, Max Effort, Opus 4.8 Fallback) competes directly with similarly capable models. Key competitors include GPT (OpenAI), Gemini (Google), and open source models like Llama (Meta) and DeepSeek. The choice between models depends on the specific use case, budget, latency requirements, and need for features like multimodality and tool calling.
For a detailed side-by-side comparison, use our comparison tool or check the overall model ranking.
Frequently Asked Questions
What is Claude Fable 5 (Adaptive Reasoning, Max Effort, Opus 4.8 Fallback)?
Claude Fable 5 (Adaptive Reasoning, Max Effort, Opus 4.8 Fallback) is an AI model developed by Anthropic. It is a text model.
How much does Claude Fable 5 (Adaptive Reasoning, Max Effort, Opus 4.8 Fallback) cost?
Claude Fable 5 (Adaptive Reasoning, Max Effort, Opus 4.8 Fallback) costs $10/1M input tokens and $50/1M output tokens. For heavy usage (e.g., a chatbot handling 100k messages/month), costs can range from $10 to $1,000 depending on volume.
How does Claude Fable 5 (Adaptive Reasoning, Max Effort, Opus 4.8 Fallback) compare with other models?
In available benchmarks, Claude Fable 5 (Adaptive Reasoning, Max Effort, Opus 4.8 Fallback) scored: Terminal-Bench Hard: 63/100, LiveBench Coding: 78.57/100, AA Coding Index: 76.5/100. See the full table above for a detailed comparison.
Is Claude Fable 5 (Adaptive Reasoning, Max Effort, Opus 4.8 Fallback) open source?
No, Claude Fable 5 (Adaptive Reasoning, Max Effort, Opus 4.8 Fallback) is a proprietary model from Anthropic. It is available via cloud API. For open source alternatives, check our open source model ranking.
What is Claude Fable 5 (Adaptive Reasoning, Max Effort, Opus 4.8 Fallback) best for?
Claude Fable 5 (Adaptive Reasoning, Max Effort, Opus 4.8 Fallback) excels at multimodal tasks including text and vision. With its large context window, it handles long documents, codebases, and extended conversations. It supports tool calling for API integrations and automation.
Last updated: July 28, 2026 • View methodology →