Anthropic released Opus 4.5 on Monday, the final model in its 4.5 series, introducing Chrome and Excel integrations.
Opus 4.5 demonstrates state-of-the-art performance across various benchmarks. These include coding benchmarks such as SWE-Bench and Terminal-bench, tool use benchmarks like tau2-bench and MCP Atlas, and general problem-solving evaluations including ARC-AGI 2 and GPQA Diamond.
The model notably achieved over 80% on SWE-Bench verified, a significant result for a coding benchmark.
Anthropic highlighted Opus’ capabilities in computer use and spreadsheets. Alongside Opus 4.5, Anthropic made its Claude for Chrome and Claude for Excel products, previously in pilot phases, more widely accessible. The Chrome extension is available to all Max users, while the Excel-focused model is accessible to Max, Team, and Enterprise users.
Opus 4.5 incorporates memory improvements for long-context operations. Dianne Na Penn, Anthropic’s head of product management for research, stated to TechCrunch, “There are improvements we made on general long context quality in training with Opus 4.5, but context windows are not going to be sufficient by themselves. Knowing the right details to remember is really important in complement to just having a longer context window.”
These memory enhancements enabled an “endless chat” feature for paid Claude users. This feature allows continuous chat without interruption when the model reaches its context window limit. The model compresses its context memory without user notification.
Many upgrades target agentic use cases, particularly scenarios where Opus functions as a lead agent overseeing Haiku-powered sub-agents. Managing such tasks requires proficient working memory. Penn noted, “This is where fundamentals like memory become really important, because Claude needs to be able to explore code bases and large documents, and also know when to backtrack and recheck something.”
Opus 4.5 enters a competitive market. OpenAI released GPT 5.1 on November 12, and Google released Gemini 3 on November 18, both new frontier models.
