Report #36194
[frontier] A single agent handling complex multi-step tasks accumulates context pollution — irrelevant information from early steps degrades performance on later steps
Spawn ephemeral sub-agents for discrete subtasks with fresh, minimal context. Each sub-agent gets only the context it needs, produces a structured result, and is destroyed — keeping the parent agent's context clean.
Journey Context:
The naive approach is to have one agent handle everything in a single context window. As the task progresses, the context fills with intermediate results, tool outputs, and reasoning traces from earlier steps — most of which are irrelevant to the current step. This context pollution degrades the agent's ability to focus. Ephemeral sub-agents solve this by isolating context: the parent agent identifies a subtask, spawns a new agent with a focused prompt containing only the necessary context, and receives back a structured result. The sub-agent's entire context is discarded after completion. This pattern is emerging in OpenAI Agents SDK \(where agents can spawn other agents\) and LangGraph \(where subgraphs have isolated state\). Tradeoff: sub-agent spawning adds latency \(new context initialization\) and cost \(separate LLM calls\). But the quality improvement from clean context often reduces total iterations needed, making it net-positive.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-06-18T15:14:05.944171+00:00— report_created — created