1 in 4 3rd Party AI Endpoints Underperform Their Advertised Models

Artificial Analysis released version 1.1 of its Endpoint Accuracy Index, which compares more than 100 serverless endpoints hosting open-weight models against reference deployments of the official weights, finding roughly one in four score below their reference. The index reruns each endpoint on BFCL v4-500, HLE-250 and AA-LCR-25, and version 1.1 raises long-context repeats from 10 to 25, cutting the average 95% confidence interval from plus or minus 4.7 to plus or minus 2.6 points, while coverage expands to six models including DeepSeek V4.1 Flash 1017, GLM-5.3, GLM-5.3 Flash, Muse Spark Open, Kimi K3 and gpt-oss-120b. Reported gaps trace to output caps that truncate answers, shorter reasoning, and a schema bug encoding string tool arguments as numbers, with GLM-5.3 endpoints scoring from 67.2% to 99.3% and all 22 DeepSeek endpoints statistically consistent with the reference.