Compress Stage — Making Context Smaller: Summarization, Pruning, Distillation

~12 min read

Compressing context means keeping only the tokens actually needed for the task at hand. Retrieved context and multi-turn tool-call history often contain duplicate or redundant information that inflates token count and cost — summarization is the main fix.

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Key points

  • Compressing context means keeping only the tokens actually needed for the task, not the full raw text of everything selected
  • Multi-turn tool-call history commonly accumulates duplicate/redundant information, inflating token count and cost
  • Context summarization is the book's main technique — condensing history into a denser representation that keeps the useful signal
  • This is lossy compression by design — discarded detail (redundant restatements) wasn't adding decision-relevant value anyway
  • Pruning (dropping irrelevant content) and distillation (extracting just key facts) pursue the same goal alongside summarization