Inkling vs. Claude Fable 5.5

Inkling is an open-weights multimodal AI model from Thinking Machines built to support customization, agentic workflows, coding, reasoning, vision, audio, and enterprise AI use cases. The model is a Mixture-of-Experts transformer with 975 billion total parameters, 41 billion active parameters, 256 routed experts per MoE layer, and six routed experts active per token. It supports context windows up to 1 million tokens and was pretrained on 45 trillion tokens across text, images, audio, and video. Inkling is designed as a broad foundation model rather than a narrowly optimized benchmark model, giving it balanced capabilities across reasoning, coding, factuality, instruction following, vision, audio, tool use, and safety. Its controllable thinking effort lets developers adjust how much computation and generated reasoning the model uses, helping teams balance quality, latency, and cost for different production needs. The model can run agentic coding tasks, use tools, create web apps, generate polished multi-page artifacts, reason over long contexts, and work through iterative refinement loops. For multimodal tasks, Inkling can process images, answer questions about visual content, transcribe and reason over audio, follow spoken instructions, and combine visual reasoning with code-based tools such as Python. Thinking Machines trained Inkling for calibration, instruction following, factual reliability, refusal behavior, and safety across multiple modalities, including evaluations for dangerous capabilities and human-AI threat vectors. Inkling is available on Tinker for fine-tuning, with 64K and 256K context options, an Inkling Playground for testing, cookbook recipes, and support for multimodal post-training workflows. Its full weights are available on Hugging Face, and deployment support is available through APIs and infrastructure partners such as TogetherAI, Fireworks, Modal, Databricks, Baseten, SGLang, vLLM, llama.cpp, and transformers.

Claude Fable 5.5 is a possible future addition to Anthropic's premium Claude Fable model line, but Anthropic has not officially announced a model under that name as of September 30, 2026. The company's current model catalog identifies Claude Fable 5.1 as the latest Fable model, alongside the newer Claude Opus 5.5 and Claude Sonnet 5.5. Anthropic positions Fable 5.1 for demanding reasoning and long-horizon agentic work requiring its highest-end model capabilities. The model provides a 1-million-token context window and supports outputs of up to 128,000 tokens. Fable 5.1 uses adaptive thinking that is always enabled and defaults to a high effort setting for more intensive reasoning. It accepts text and images as input and generates text output, with Anthropic listing June 2026 as both its reliable knowledge cutoff and training-data cutoff. Fable 5.1 costs $10 per million input tokens and $50 per million output tokens, with cache reads priced at $0.25 per million tokens. It is officially supported through the Claude API, Amazon Bedrock, Google Cloud, Microsoft Foundry, and Claude Platform on AWS. Anthropic's September releases have expanded the Claude 5.5 generation with Opus 5.5 and Sonnet 5.5, but its official model catalog has not similarly replaced Fable 5.1 with Fable 5.5. Anthropic's Trust Center likewise lists documentation for Claude Mythos 5.1 and Fable 5.1 as well as Opus 5.5 and Sonnet 5.5, without documentation for a Fable 5.5 model. Consequently, claims about Claude Fable 5.5's performance, benchmarks, context limits, pricing, capabilities, or release date should be considered unconfirmed until Anthropic publishes official information.