Vals AI released MysteryMechanism, a benchmark testing whether agents can rediscover sealed scientific mathematical mechanisms via bounded experiments. GPT-6 Astra led at 53.2% accuracy versus Claude Fable 5.1 at 47.8% and Claude Opus 5 at 37.4%; Astra also cost about $1.77 per test, roughly one-third of second-place Fable 5.1 at $5.63.

Key Takeaways

  • ✓MysteryMechanism tests rediscovering sealed scientific mechanisms via bounded experiments
  • ✓GPT-6 Astra leads at 53.2% vs Claude Fable 5.1 47.8% and Claude Opus 5 37.4%
  • ✓Astra costs about $1.77/test, roughly one-third of second-place Fable 5.1 at $5.63
⚡

Key Decision Metrics at a Glance

TL;DR Verdict
🏆 Benchmark RankRank
GPT-6 Astra leads at 53.2% vs Claude Fable 5.1 47.8% and Claude Opus 5 37.4%
Full Leaderboard→
💰 Cost & PlansCompare
GPT-6 Astra · in: $10 / out: $50
Compare Plans↗
🛠️ Ecosystem & IDERules
MysteryMechanism · Vals AI · GPT-6 Astra
Setup IDE Rules↗
🧭

Turn your technical choice into a development budget

Compare 40 dev plans & simulate token costs vs $20/mo subscriptions

⚔️ Compare Model→💰 Compare plans & limits↗
Action HubReady to adopt this in production?

Benchmark side-by-side against alternatives, or calculate monthly token cost vs subscription break-even.

⚔️ Launch VS Compare→💳 View Plans↗
Up NextVals Live Terminal-Bench 4.0: GPT-6 Astra Leads at 57.1%
Read Now→