Meta Releases Muse Spark 1.3 with Better Coding and Long-Horizon Agent Tasks

Meta released its most powerful AI model, Muse Spark 1.3, on September 2, 2026, focusing on coding and long-horizon agent workflows. Meta's Chief AI Officer Alexandr Wang says it beats OpenAI's GPT-5.6 Sol on coding and matches Anthropic's Claude Fable 5.1. Pricing stays the same as the previous version via Meta Model API: $1.25 per million input tokens, $0.15 for cached input, and $4.25 per million output tokens. The API is seeing strong adoption, with some developers using trillions of tokens weekly. The new model will be integrated into Instagram, Facebook, and Meta AI assistant. Compared to 1.2, the 1.3 version reduces unnecessary code iterations, cuts tool calls by about 20%, and uses 25% fewer tokens for the same tasks. It handles multiple workflows in one long thread, proactively fixes plan gaps, asks clarifying questions on vague instructions, and seeks confirmation before key actions. It retains detailed requirements better in multi-step tasks and reduces hallucinations.