Sources
Elvis Saravia's AI Agents Weekly: Sonnet 5 Checks Its Own Output Without Being Asked
Saravia's roundup characterizes Claude Sonnet 5 as making plans, driving browsers and terminals, and finishing multi-step tasks where prior Sonnets stopped short — notably self-checking output unprompted. Anthropic puts it close to Opus 4.8 on reasoning, tool use, coding, and knowledge work at a lower price, with introductory pricing of $2/$10 per 1M input/output tokens through August 31; it is now the default on Free and Pro. The same issue covers LongCat-2.0, hosted X MCP, Grok Voice Agent Builder, and Cursor for iOS. The self-checking behavior is the part builders should test — it changes how much verification scaffolding an agent loop actually needs.
↳ Follow the thread