Roboflow
Anthropic

Anthropic: Claude Fable 5.1

Claude Fable 5.1 Overview

Claude Fable 5.1 is a proprietary multimodal model from Anthropic in the Mythos-class tier of the Claude 5 family, positioned above Claude Opus for demanding reasoning and long-horizon agentic work. It accepts text and images as input and returns text, with a one million token context window and a maximum output of 128 thousand tokens. Adaptive thinking is always on, and an effort parameter controls how much reasoning the model applies to a given request. Anthropic reports a reliable knowledge and training data cutoff of June 2026. Claude Fable 5.1 and Claude Mythos 5.1 share the same underlying model; the difference between them is the set of safety classifiers applied to dual-use cybersecurity and biology requests.

On the vision side, Anthropic documents improvements in reading dense charts, financial filings, and tables nested inside PDF documents, which extends the model toward document understanding, chart question answering, and spreadsheet and slide work. Reported evaluations cover agentic scientific research on Terminal-Bench-Science 0.1, agentic coding on Terminal-Bench 4.0, computer use on OSWorld 2.0, and multidisciplinary reasoning on Humanity's Last Exam. Model weights are not published.

Claude Fable 5.1 Interactive Demo

Model settings

Extended thinking

Max output tokens

Default 65,536 · max 65,536

Sign in to adjust thinking and output length per run.

Results appear here. Add an image or pick an example to run Claude Fable 5.1.

Claude Fable 5.1 Details & Performance

Details

Resources

Vision Tasks

CaptioningChart Question AnsweringClassificationDocument Question AnsweringImage TaggingMulti-Label ClassificationOCRObject DetectionVision LanguageVisual Question Answering

Features

Foundation VisionLLMs with Vision CapabilitiesMultimodal Vision

Usage

Past 30 Days

Performance

Avg. Latency

Claude Fable 5.1 Vision Evals

Vision Evals is Roboflow's ground-truth benchmark: every model runs the same real-world samples across six vision tasks, and answers are scored against ground truth.

Evals updated September 5, 2026Pricing updated September 13, 2026

Overall score#8 of 53
81.3%
Avg cost / sample#53 of 53
$0.035
Avg speed / sample#25 of 53
8.28s
Avg tokens / sample
2.2K

Strengths and weaknesses

Claude Fable 5.1 averages 81.3% across the six Vision Evals tasks, ranking #8 of 53 models overall.

It places in the top three for OCR.

Its weakest relative showing is Counting, ranking #14 of 53 at 69.4%.

At $0.035 per sample it is the 53rd cheapest of the 53 benchmarked models, and its average inference time of 8.3s per sample makes it the 25th fastest.

Performance profile

Field medianClaude Fable 5.1

Field medians: Object Detection 53.9%, Counting 56.8%, Identification 84.4%, OCR 88.7%, Data Extraction 84.5%, Reasoning 54.1%.

Results by task

TaskScoreField (0 to 100)RankCost / sampleSpeed
Object Detection (low)
61.4%
±0.5, Mean of 3 runs, range 61.0 to 62.0
#9 of 53$0.06011.98s
Object Detection (high)
65.0%
±0.4, Mean of 3 runs, range 64.6 to 65.3
#10 of 17$0.07817.13s
Counting (low)
69.4%
±2.7, Mean of 3 runs, range 66.2 to 71.6
#14 of 53$0.0195.75s
Counting (high)
73.0%
±4.7, Mean of 3 runs, range 67.6 to 77.0
#11 of 17$0.0236.53s
Identification (low)
97.9%
±1.6, Mean of 3 runs, range 96.9 to 100.0
#5 of 53$0.0135.01s
Identification (high)
96.9%
±3.1, Mean of 3 runs, range 93.8 to 100.0
#3 of 17$0.0144.95s
OCR (low)
94.0%
±0.4, Mean of 3 runs, range 93.6 to 94.4
#2 of 53$0.0399.76s
OCR (high)
93.6%
±0.2, Mean of 3 runs, range 93.5 to 93.9
#1 of 17$0.0399.66s
Data Extraction (low)
93.1%
±0.5, Mean of 3 runs, range 92.8 to 93.8
#7 of 53$0.0164.83s
Data Extraction (high)
93.5%
±0.5, Mean of 3 runs, range 92.8 to 93.8
#5 of 17$0.0164.83s
Reasoning (low)
72.0%
±1.3, Mean of 3 runs, range 70.9 to 73.5
#11 of 53$0.0195.94s
Reasoning (high)
73.1%
±2.0, Mean of 3 runs, range 71.5 to 75.5
#13 of 39$0.0288.05s
  • Thinking longer helps: 3.6 points higher on object detection at high effort for 1.3x the cost and 1.4x the latency.
  • Thinking longer helps: 3.6 points higher on counting at high effort for 1.2x the cost and 1.1x the latency.
  • Thinking longer does not help: 1 points lower on identification at high effort for 1.1x the cost and 1x the latency.
  • Thinking longer does not help: 0.4 points lower on ocr at high effort for 1x the cost and 1x the latency.
  • Thinking longer helps: 0.3 points higher on data extraction at high effort for 1x the cost and 1x the latency.
  • Thinking longer helps: 1.1 points higher on reasoning at high effort for 1.5x the cost and 1.4x the latency.

Price vs. performance

Score vs. cost

Overall benchmark score against estimated cost per sample, on a log scale. Upper-left is the sweet spot: high quality at low cost.

52 models on the current benchmark · scores and efficiency pooled across all six tasks at low effort · Claude Fable 5.1 highlighted

Claude Fable 5.1 scores are the mean of 3 runs per task at both low and high effort · Methodology

View all Vision Evals →

Claude Fable 5.1 Pricing

Claude Fable 5.1 costs $10.00 per 1M input tokens and $50.00 per 1M output tokens.

Input$10.00 / 1M tokens
Output$50.00 / 1M tokens
Cached input$0.250 / 1M tokens

Pricing updated Sep 13, 2026

Alternatives to Claude Fable 5.1

Other models worth comparing for similar use cases.

OpenAI
GPT-6 Astra
GPT-6 Astra is a proprietary multimodal reasoning model from OpenAI that accepts text and image input and produces text output. It is positioned as the company's flagship system for long-horizon end-to-end work spanning complex reasoning, software engineering, computer use, browsing, research and document creation. The model exposes a graduated reasoning effort control with low, medium, high, xhigh and max settings, and it accepts a change to that setting partway through a conversation rather than only at request time. It launches as a single tier with no smaller mini or nano variants, carries a context window of roughly 1.05 million tokens with a maximum output of 128,000 tokens, and reports a knowledge cutoff of April 30, 2026.OpenAI reports evaluation results across agentic, scientific and security benchmarks, including 96.0% on GPQA Diamond, 64.6% on Terminal-Bench Science, 72.6% on OSWorld 2.0, and a perfect score on ExploitBench, along with near saturation on FrontierMath Tier 4 and ARC-AGI-3. The model supports computer use, structured outputs, streaming, programmatic tool calling, multi-agent orchestration, prompt caching and persisted reasoning, and it keeps earlier context windows searchable so it can recover requirements or tool outputs from previous turns. OpenAI describes Astra as the first of its models to cross the Critical cybersecurity capability threshold under its Preparedness Framework.
Google
Gemini 3.1 Pro
Gemini 3.1 Pro is a proprietary multimodal model from Google’s Gemini 3 series, released in early 2026 and designed for advanced reasoning across large multimodal datasets. It accepts text, images, audio, video, and documents, supporting up to a 1-million-token input context with up to 64k output tokens. Compared with Gemini 3 Pro, it improves long-context synthesis and multi-step reasoning, enabling more reliable analysis of large documents, datasets, and software codebases.The model also advances visual understanding and grounding, allowing it to interpret UI screenshots, diagrams, and real-world scenes while referencing specific regions within images or video. These capabilities make Gemini 3.1 Pro well suited for multimodal workflows involving document processing, interface analysis, robotics research, and complex visual reasoning.
Anthropic
Claude Opus 4.7
Claude Opus 4.7 is a proprietary multimodal language model developed by Anthropic, released on April 16, 2026. It is designed for agentic coding, long-horizon task execution, and enterprise knowledge work. The model supports text and vision inputs and operates with a context window of up to 1,000,000 tokens. It introduces adaptive thinking, which dynamically allocates reasoning based on task complexity, along with configurable effort controls including a new xhigh setting that sits between the existing high and max levels. It achieves 87.6% on SWE-bench Verified and 78.0% on OSWorld-Verified, reflecting strong performance on autonomous software engineering and computer use tasks respectively.Compared to Claude Opus 4.6, version 4.7 shows improved instruction following and higher reliability in extended agentic tasks. Vision capabilities now support high-resolution inputs up to 2,576px on the long edge (~3.75 megapixels), more than three times the resolution of prior Claude models, enabling finer interpretation of dense diagrams, UI screenshots, and document layouts. These improvements, combined with self-verification on long-running tasks and a new task budget system for controlling agentic loops, make it well-suited for complex software engineering, technical analysis, and multimodal vision workflows.
Meta
Muse Spark 1.3
Muse Spark 1.3 is a proprietary multimodal reasoning model from Meta Superintelligence Labs and the fourth Muse Spark release in five months, arriving on September 2, 2026. It takes text, images, video, and document files as input and returns text, and it operates over a context window of 1,048,576 tokens. Meta trains the model for long-horizon agentic work, so it carries accumulated context and prior tool results forward across many turns, reconciles messy or conflicting inputs, and asks for clarification when a task is underspecified. Visual inputs such as screenshots and video clips feed a reasoning loop that runs against a real execution environment rather than a scripted sequence of steps.The model exposes graded reasoning effort settings. An xhigh configuration is generally available at launch, while a max reasoning configuration aimed at harder reasoning and agentic problems arrives after further safety testing. Artificial Analysis measures Muse Spark 1.3 (max) at 62 on its Intelligence Index and the xhigh configuration at 61, with agentic tool-use evaluations driving most of the gain over Muse Spark 1.2; max reaches 52% on Tau3-Bench Banking by spending more turns and reasoning tokens than xhigh. Prior Muse Spark versions emit bounding box coordinates, transcriptions, and structured field extractions from images on Roboflow Vision Evals.
Qwen
Qwen3.8 Max
Qwen3.8 Max is the flagship tier of Alibaba's Qwen3.8 family, a sparse mixture-of-experts multimodal model with roughly 2.4 trillion total parameters of which about 95 billion activate per token, which keeps serving cost and latency well below what the total parameter count would imply. It builds on the architectural foundation established by Qwen3.5 and accepts text, images, video, and documents as input while producing text output. Reported context handling reaches close to one million tokens, with a maximum generation length of 131,072 tokens, so the model is aimed at long-horizon agentic work such as repository-scale coding, multi-step research, data analysis, and office document workflows.For vision work the model performs image and video understanding, document and chart interpretation, text recognition inside images, and grounded visual question answering, and Alibaba reports gains concentrated in multimodal and agentic evaluation categories rather than general reasoning. Published figures include 86.6 on Terminal-Bench 2.1, 67.7 on SWE-bench Pro, 93.0 on PaperBench, 82.8 on IFBench, and 92.6 on GPQA Diamond. It is the first model in the Max tier of the Qwen line for which the team states weights will be released publicly, alongside a smaller Qwen3.8 27B checkpoint. No training or safety model card has been published.
MoonshotAI
Kimi K3
Kimi K3 is a sparse Mixture-of-Experts large language model developed by Moonshot AI, with 2.8 trillion total parameters and a 1-million-token context window. The model activates 16 out of 896 experts per token using the Stable LatentMoE framework, and is built on two architectural innovations: Kimi Delta Attention (KDA), a hybrid linear attention mechanism that enables up to 6.3x faster decoding in long-context settings, and Attention Residuals (AttnRes), which selectively retrieves representations across model depth and delivers roughly 25% higher training efficiency. Together with refined training and data recipes, these structural advances yield approximately 2.5x better overall scaling efficiency compared to its predecessor Kimi K2. The model applies quantization-aware training from the supervised fine-tuning stage onward, using MXFP4 weights with MXFP8 activations for hardware compatibility. Thinking mode is always enabled at launch, with reasoning effort configurable via the reasoning_effort field.Kimi K3 supports native visual understanding alongside text, accepting image inputs for tasks that combine software engineering and visual reasoning. It targets long-horizon coding, knowledge work, and agentic workflows, and ships in two variants: K3 Max for general chat and agent tasks, and K3 Swarm Max for large-scale parallel processing across many coordinated sub-agents. The model is compatible with the OpenAI SDK via an OpenAI-compatible API. Full model weights are scheduled for release by July 27, 2026 under a Modified MIT license, following the open-weight pattern established by the Kimi K2 model family. A technical report with full architecture, training, and evaluation details is expected to accompany the weights release.

Other Anthropic Fable models

Other versions in the same family as Claude Fable 5.1.

Claude Fable 5.1 License

Proprietary

Claude Fable 5.1 is proprietary: the weights are not distributed, and the Claude Fable 5.1 license is the vendor's commercial terms of service that you accept when you call the API.

Commercial use
Permitted under the vendor terms, typically metered per token or per request, with the vendor usage policy applying to your inputs and outputs.
Modification
Not available. Claude Fable 5.1 weights are closed, so you can configure prompts and use vendor-hosted fine-tuning where it is offered, but you cannot modify the model itself.
Redistribution
Not permitted. You cannot self-host or resell the model; you build on the hosted API instead.

Vendor terms govern data retention, whether your inputs can be trained on, rate limits, and regional availability, and they can change with notice. Review them if you handle regulated or customer data.

Do I need a commercial license for Claude Fable 5.1?

Proprietary terms are set by the vendor rather than negotiated per project, and no open-source obligation attaches to your code. If you would rather deploy a model whose commercial license is included in your plan — on Roboflow Managed Cloud or a Self-Hosted Inference Server — Roboflow's licensing page lists the supported alternatives to Claude Fable 5.1.

Do not hesitate to reach out with questions for your commercial project — our team will help you start solving business problems on the first call. See Roboflow commercial licensing for the models included in each plan.

Talk to sales

This model is proprietary. The author retains all rights, and use of the model is governed by their specific terms of service or license agreement.

Commercial use depends on the terms set by the model author. Most proprietary commercial models require a paid subscription, API key, or per-call billing. Check the provider’s pricing and terms-of-service for details.

License information is provided as a guide and is not legal advice.

Frequently Asked Questions About Claude Fable 5.1 Vision

Yes. Claude Fable 5.1 accepts image input and handles OCR, data extraction, object counting, identification, visual reasoning, and object detection. On Roboflow's Vision Evals its strongest task is OCR at 94% (#2 of 53 at low effort). You can test it on your own image in the demo above.

Yes, and it is one of the model's strongest vision skills: its transcriptions match the ground truth 94% on average (#2 of 53 at low effort) on Vision Evals OCR. Pulling specific fields out of documents (data extraction) scores 93.1%.

It's serviceable. On Vision Evals, Claude Fable 5.1 scores 61.4% mAP@50 on object detection (#9 of 53 at low effort) and 69.4% judge-graded accuracy on object counting.

On our benchmark's task mix, Claude Fable 5.1 averages $0.04 per sample at $10.00 per 1M input and $50.00 per 1M output tokens (#53 of 53 on cost), with an average speed of 8.3s per sample across the benchmark. Actual cost depends on your images and prompts.

On the overall Vision Evals ranking, Claude Fable 5.1 sits #8 of 53 at 81.3%, just behind Gemini 3.6 Flash (83%) and just ahead of Muse Spark 1.1 (80.5%). See the full side-by-side: Claude Fable 5.1 vs Gemini 3.6 Flash.