Long-running agents beyond prompt engineering
A report from n8n explores how building long-running AI agents requires moving past prompt engineering to create deterministic control harnesses. Relying on models to perform self-evaluation introduces points of hallucination and context drift into workflows. The article highlights techniques to track and trim conversation histories to preserve semantic focus during extended tasks.
Key Takeaways
- Building reliable AI agents requires moving beyond prompt engineering to construct deterministic software harnesses.
While a model simply receives text and generates a response, the agent serves as the execution layer that manages system logic and tool integration.
- When developers depend on models to evaluate their own performance or make decisions mid-task, they increase the likelihood of hallucination and operational drift.
Instead, the surrounding application harness should enforce output validation and schedule tasks independently of model self-direction.
- Developers can monitor token distribution using specialized tools like Gumloop's Context Usage Meter, which categorizes usage across system instructions, abilities, subagents, and chat history.
To prevent context rot in extended workflows, developers can compress context using solutions such as Google's ADK Context Compaction, which applies a sliding window to summarize earlier workflow event histories once specific threshold counts are reached.
- Relying on an LLM to evaluate its own output introduces points of hallucination and context drift during agent execution.
Models only process text inputs to create text outputs, whereas agents represent the execution layer that runs tool logic.
- Google's ADK Context Compaction uses a sliding window approach to summarize older workflow event data when hit thresholds occur.

Building reliable AI agents requires moving beyond prompt engineering to construct deterministic software harnesses. While a model simply receives text and generates a response, the agent serves as the execution layer that manages system logic and tool integration. When developers depend on models to evaluate their own performance or make decisions mid-task, they increase the likelihood of hallucination and operational drift.
Instead, the surrounding application harness should enforce output validation and schedule tasks independently of model self-direction. Because every LLM query resends the complete dialogue history, context management becomes essential for long-running sessions. Developers can monitor token distribution using specialized tools like Gumloop's Context Usage Meter, which categorizes usage across system instructions, abilities, subagents, and chat history.
To prevent context rot in extended workflows, developers can compress context using solutions such as Google's ADK Context Compaction, which applies a sliding window to summarize earlier workflow event histories once specific threshold counts are reached. Relying on an LLM to evaluate its own output introduces points of hallucination and context drift during agent execution. Models only process text inputs to create text outputs, whereas agents represent the execution layer that runs tool logic.
For more details please read the original article at n8n Blog.
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