observations-are-83-percent-of-tokens-mask-stale-outputs-not-summarize
Tool output observations constitute 83.9% of total agent tokens in typical sessions. Summarizing stale observations costs 5–7% compute overhead and still loses precision versus the original. Replacing superseded tool outputs with [Previous N lines elided] (observation masking) achieves equivalent context freeing at zero overhead. Apply proactively whenever a newer call to the same tool makes an earlier output obsolete.