A simple loop detector for stuck agents
Warm-Reaction-456 · reddit · 2026-07-20
The author describes a practical detector for autonomous agents that get stuck in tool-call loops.
Approach
- Fingerprint each tool call as name + hash(arguments)
- Keep a sliding window of the last 20 fingerprints
- Detect short repeating cycles of length 1–3, such as A A A, A B A B A B, or A B C A B C A B C
- Escalate gradually: first and second hits inject nudges, the third hit halts the turn
Limits
- Only catches byte-identical argument loops
- Misses loops with slightly different arguments
- Does not detect semantic no-progress loops
The author asks how others detect stuck agents, especially when the agent appears to be making “progress” but is actually going nowhere.
Related event: Catching Agent Infinite Loops: Fingerprint & Sliding Window(6 posts)→
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