Anthropic Releases Opus 4.6; Claude 5 Sonnet Spotted in Vertex AI Logs

Anthropic released Opus 4.6 on February 5 with expanded capabilities. A model identifier 'claude-sonnet-5@20260203' appeared in Google Vertex AI error logs, suggesting Claude 5 Sonnet is in testing. Leaks indicate Sonnet 5 may deliver Opus-comparable performance at 50% lower cost, continuing the pattern of capability democratization across model tiers.