A paper identifies a systematic evaluation flaw in skill-enabled agents where overall gains can mask degraded performance on retrieval tasks; RAE proposed as a fix.
Long-horizon agent state and skill-file research
Google SKILL.state cuts agent token use 94% while improving accuracy
Long-horizon agent tasks often balloon in token use as conversation history grows. SKILL.state shows that structured state can replace full history at a fraction of the cost, cutting token use roughly 94% on a 100-step benchmark while modestly improving accuracy.
The full picture
SKILL.state, from researchers at Google and Purdue, replaces the growing conversation transcript in long-horizon agents with a small structured state. The model receives only skill instructions, the structured state, and the latest observation at each step; reasoning traces are discarded. Prompt size stays roughly constant as task length grows because only validated state updates are retained. On a 100-step warehouse task with Gemini 3 Flash, SKILL.state scored 0.94 using 65,408 tokens, compared to a LangGraph-style baseline scoring 0.91 and using 1,062,387 tokens, a 16.2x token difference. The approach is limited to scenarios where all information needed downstream can be captured in the state schema.
How it developed
Data shows Google at 3.2 quadrillion tokens/month, agents 71% of OpenRouter traffic, Goldman projects 24x growth by 2030
Microsoft paper reported showing skill distillation from 35-50 trajectories recovers 55%-100%+ of reasoning model performance gap at 2.9-4.5x lower token cost
Harness-of-Harness scores 71.52 vs 58.24 for naive continuation on GameCraft-Bench
Google and Purdue's SKILL.state, published September 3, replaced growing agent transcripts with a structured state, cutting tokens 94% on a 100-step task while holding accuracy at 0.94 versus a baseline's 0.91.
ByteDance's Chain-of-Experience, published September 4, offered a direct contrast: keeping full attempt history in context raised accuracy from 66.8% to 79.3% across six benchmarks. Amazon and Microsoft's SPACE added a third angle, training agents to batch safe sequential actions, raising ScienceWorld success from 35.9% to 67.2% while cutting LLM rounds from 10.2 to 5.2.
ContextPilot paper described, using RL-trained context management
Three benchmarks published September 2 document frontier model struggles on extended tasks: 17 models averaged a 6.4% pass rate on multi-step terminal tasks, 10 of 17 solving zero; the best agent scored 51.3/100 after 12 hours; and the top setup on year-long decisions reached 27.3% of human earnings.
Investor Chamath Palihapitiya, at Stanford's AI Club, warned AI investment could reach a trough of disillusionment if these limitations are not addressed. A separate paper found agent traces compress into finite-state machines with 7 to 43 states.
A head-to-head experiment published September 1 comparing OpenClaw 2.0 and Hermes agents on a video generation task found that self-verification depth, not model capability, drove token consumption: OpenClaw used approximately 2.1M tokens with 10 self-fixes, Hermes approximately 2.9M with 20, the extra roughly 800K tokens spent on Hermes's render-checking harness measuring frame timing, seam visibility, and spec compliance.
The experiment frames a portion of agent token use as QA allocation, raising the question of how much compute agents should spend proving their work before returning results.
Multiple papers on how agents should manage state in long tasks, reported August 30-31, reached two conclusions: structured state cuts token use and raises accuracy, while skill file injection consistently lowers performance.
Google and Purdue's SKILL.state reduced tokens 94% on a 100-step warehouse task; Meta's EvoHarness-RL raised ALFWorld accuracy from 47.9% to 96.9%; Nvidia's ACES found skill document scores correlate near-zero with runtime gains; and WebDev-Skills-Bench found skill injection lowered pass rates across all tested models.
Paper testing eight leading models on year-long decision tasks finds best setup achieves 27.3% of human earnings
WebDev-Skills-Bench finds skill file injection lowers pass rates and raises token costs across all four tested models
Nvidia ACES finds skill document scores correlate near-zero with measured runtime improvement
Paper argues on-policy distillation outperforms GRPO for long-horizon agent training
Sources
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