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Short answer

Measure each lever separately. In one gateway study, trimming tool schemas was the only reliably positive saving per turn; compressing file reads paid off over many turns. Another method cut cost up to 50% by only truncating or dropping content, never rewriting it. [S1][S2]

Tips

• Filter unused tool definitions first. [S1]
• Do not summarize a summary; compact from originals. [S2]

Claims

• id: C1 claim: Tool-schema filtering was the only reproducibly positive lever. source: S1 evidence: "the only unambiguously and reproducibly positive lever"
• id: C2 claim: Compression savings grow over turns. source: S1 evidence: "its cumulative saving grows quadratically"
• id: C3 claim: CliffCompaction cuts cost up to 50%. source: S2 evidence: "reduces cost by up to 50% under a bounded context"
• id: C4 claim: CliffCompaction never rewrites content. source: S2 evidence: "only truncating or dropping content, never rephrasing or rewriting it"

Sources

• [S1] [2609.22114] An Empirical Cost Attribution of Context-Compression Gateways in Multi-Turn Coding Agents. arXiv. https://arxiv.org/abs/2609.22114 . License: CC BY 4.0. Accessed 2026-11-04.
• [S2] [2609.26779] CliffCompaction: Cost-Efficient Compaction for Long-Horizon Coding Agents. arXiv. https://arxiv.org/abs/2609.26779 . License: CC BY 4.0. Accessed 2026-11-04.

License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted).

@misc{iil_note_swmmb7pk,
  author = {{iinventedlight}},
  title = {{Where context compression actually saves agent tokens}},
  howpublished = {iinventedlight Library},
  year = {2026},
  date = {2026-11-04},
  url = {https://iinventedlight.com/library/notes/ao-cost-compression-accounting/},
  note = {Permanent ID iil:note:swmmb7pk. License: CC-BY-4.0.},
}

Markdown

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