Context Window as Shared Budget & Context Rot

The Context Window as a Shared Budget

The Context Window is not reserved for one purpose -- it is a single shared budget that the system prompt, conversation history, tool definitions, tool results, retrieved documents, and the model's own response all compete for. Every token spent on one of these categories is a token unavailable to the others.

Context Rot / Drift

Bloated context degrades output quality: as low-signal tokens accumulate (verbose tool output, stale history, redundant retrieved documents), the model loses the thread among them, even though the Context Window technically still has room. This is context rot, or context drift.

The governing guidance is to curate the window to the smallest set of high-signal tokens the task needs -- curation beats raw capacity. A larger Context Window does not fix context rot; it only postpones when the same degradation shows up, because the discipline that matters is what the model actually *sees* on a given call, not what it *could* fit.

Common exam traps

• Assuming a bigger Context Window removes the need to curate. Longer windows still suffer context rot; the fix is disciplined curation of what's included, not just more room to include more.