−3%
Auto-generated configs reduce success
ETH Zürich↗
LLM-generated AGENTS.md files cut agent success by 3% and increase costs
20%+. Human-written files only marginally help (+4%). Most repos would do
better deleting their config than running /init.
19%
Experienced devs slower with bad context
METR · controlled study↗
16 senior developers in a controlled study were 19% slower with AI tools,
despite feeling 24% faster. The 39-point perception gap is the
cost of context failure.
40%
Sweet spot beats max utilization
Dex Horthy · HumanLayer↗
Using 40% of the context window outperforms using 90%.
A focused 300-token context can outperform an unfocused 113K-token context.
More tokens is not the answer.
85% drop
Context degrades on a curve
Anthropic · Manus production↗
At 60% capacity context is safe. At 70% precision drops.
At 85% hallucinations begin. Compact proactively. Never wait for
the auto-compact at 95%.
~150max
The instruction budget is finite
Frontier LLM benchmarks↗
Frontier models follow 150–200 instructions consistently. Claude Code’s
system prompt already uses ~50. Every line in your CLAUDE.md
competes with the actual task for attention.
10x
Stable prefixes cut cost 10x
Manus · KV-cache law↗
Cached tokens cost 10× less than uncached. Keep system instructions
and tool definitions static; append dynamic content at the end. A single
changed token at the start invalidates the entire cache.