There are suspicions that Anthropic has quietly gray-launched its latest flagship model, Fable 5.5. At present, although the Claude web interface still identifies it as Fable 5.1, the backend has already been switched over to the new model. Developers can confirm this by running specific code tests. Multiple practical tests have shown that Fable 5.5 exhibits notable enhancements compared to its previous iteration. It can accurately accomplish a range of high-difficulty tasks without the need for intricate prompts. For instance, it can precisely sketch specific game controllers, generate a diverse array of Superman-themed 3D animations using pure JavaScript, and directly produce 3D pixel web pages with seamless interactions. In tests involving the creation of interactive 3D jellyfish, its performance even outstripped that of GPT-6.1 Sol. This new model leverages Anthropic's cutting-edge Fable pre-training system, significantly expanding the upper bounds of its knowledge and capabilities. However, there is still room for improvement in its token efficiency. Recently, Anthropic has rapidly completed the 5.5 version updates for products like Opus and Sonnet, with Haiku 5.5 also slated for imminent release. It is expected that Fable 5.5 will be officially launched in the near future, further escalating competition in the AI sector.