Context Engineering: Memory, Compaction, and Tool Clearing for Production Agents
Most production AI agent failures don't happen because the model ran out of context. They happen because the model drifted long before it hit the limit. Forrester has named "agent drift" the silent killer of AI-accelerated development — and Forrester research from 2025 shows that nearly 65% of enterprise AI failures trace back to context drift or memory loss during multi-step reasoning, not raw token exhaustion.
The distinction matters. A hard context limit is clean: the API rejects the request, the agent stops, you get an error you can handle. Context rot is insidious: the model keeps running, keeps generating output, but performance quietly degrades. GPT-4's accuracy drops from 98.1% to 64.1% based solely on where in the context window information is positioned. You don't get an error signal — you get subtly wrong answers.
This post covers the three primary tools for managing context in production agents — compaction, tool-result clearing, and external memory — along with the practical strategies for applying them before your agent drifts.
