Anthropic Claude Opus 5, the new-generation flagship. It approaches the frontier intelligence of Fable 5 for roughly half the cost, which makes it the best-value high-end option. Against Opus 4.8 it roughly doubles coding performance on Frontier-Bench, scores about three times the next-best model on novel problem solving, and leads clearly on computer use and scientific research; charts and interactive output are noticeably better too. Its most praised trait is thoroughness: it verifies its own work, iterates carefully, and catches logical errors before acting. Supports very long context for whole-codebase or multi-document analysis, plus a reasoning-effort dropdown (five levels, default high), an option to show the thinking process, web search, and image and document upload. Reserve it for the hardest work such as large refactors, complex architecture design, and deep research; use Sonnet 5 or Haiku 4.5 for light everyday chat. If you need to search the web for information, please turn on the "Web Search" switch. Maximum context window (input and output combined): about 1,000,000 tokens. Maximum output per reply: about 64,000 tokens (model reasoning, if any, counts toward this limit). Maximum total upload size per request: 256MB (all files and message content combined). Accepted document formats: pdf, docx, xlsx, pptx, txt, csv (file content is provided to the model as extracted text). Accepted image formats: gif, jpeg, jpg, png, webp. Animated GIF images are analyzed using only the first frame. Maximum number of images: 600. When uploading more than 20 images, each side must be at most 2,000 pixels. Maximum size per image: 10MB (base64-encoded). Maximum total image size per message: 20MB (text and history share the same request size limit; uploads close to the limit may still be rejected). Image dimensions: 200 to 8,000 pixels per side. Output content formats: Text/Image This module supports continuous conversations. AI can make mistakes. Please verify important information.