AI Model Pricing in 2026: GPT-5.6, Grok 4.5, Muse Spark, and Claude Fable 5 Compared

GPT-5.6 Sol, Grok 4.5, Meta Muse Spark 1.1, and Claude Fable 5 all sit in the frontier tier with pricing structures that diverge significantly. Claude Fable 5 leads with a 1M+ token context window and cached token discounts, while GPT-5.6 Sol and Claude Fable 5 offer extended reasoning modes costing 3-5x more per call.