HIGH Reasoning Sweet Spot for Anthropic Fable and OpenAI GPT 5.6

DETAILED EXPLANATION

6 Sol and Anthropic Claude Fable 5. 6 Sol excels at agentic coding and long horizon tasks but is far more persistent than its predecessor, sometimes burning over 15 percent of a 5 hour usage window through aggressive sub agent spawning, so OpenAI recommends sticking to High rather than Maximum reasoning.

Claude Fable 5, by contrast, is strong at reliable parallel sub agent orchestration, making it better suited to act as a commander that delegates mechanical work to cheaper sub agents. For both models, higher reasoning tiers beyond High show diminishing returns relative to their added cost.