METR, the nonprofit AI evaluator, published an independent assessment on November 5 after spending 11 weeks inside Anthropic, from August 12 to October 29, reviewing internal data and interviewing staff. Its central finding: Anthropic is likely improving model capabilities on well-specified tasks at around twice the rate it did between March 2024 and October 2025.

Using AECI, Anthropic's benchmark capability index, METR estimates progress has run 1.9 times faster since October 2025, with a 95% confidence interval of 1.5 to 2.8 times — roughly two years of historical progress in one year. METR says it is confident faster growth in training compute does not explain the jump, and its subjective guess is that perhaps 80% of the current acceleration is due to AI assisting the research itself, though it stresses the estimate is highly uncertain and the true figure could be closer to 1.3 or 3 times.

The caveat is built into the report: Anthropic held unilateral redaction rights and, METR says, redacted a majority of the evidence it found most informative. METR also says Anthropic's public August risk report overall understates the acceleration that was occurring, and that it is plausible the company's own 2x acceleration warning threshold had already been crossed.