GPT-5.6 Sol Leads in Agent Benchmarks

RajmaChawala · reddit · 2026-07-14

The post compares frontier models like GPT-5.6 Sol, Claude Fable 5, and Grok 4.5 (released the same day), focusing on their performance in agent scenarios.

Key Information

GPT-5.6 Sol outperforms Claude Fable 5 by 13.1 points on Agents' Last Exam, scoring 53.6 vs 40.5.
Achieves 88.8% on Terminal-Bench 2.1.
Priced lower than Fable 5, which the author considers a better deal for similar or superior agent capabilities.

Caveats

Independent reviewers note Fable 5 remains stronger in architectural reasoning and planning.
OpenAI withheld long-context recall data, which the author finds suspicious as it is typically a known weak point.
The author also mentions the simultaneous release of Grok 4.5 and the ongoing absence of Google's Gemini 3.5 Pro, marking the first time all major frontier labs are competing head-to-head simultaneously.

The post concludes with a video breakdown and a practical question: which model are people actually using for daily tasks now?

Original post →

GPT-5.6 Sol Leads in Agent Benchmarks

More from Models