Report #83251
[cost\_intel] Tool-use agent loops with >5 steps failing due to plan rigidity in instruct models
Deploy o1 or o3-mini for agent orchestration when tool dependencies form DAGs deeper than 3 levels; use GPT-4o only for single-tool or linear 2-step chains
Journey Context:
Instruct models fail at backtracking in multi-step tool use: once they commit to a tool sequence, they hallucinate successful intermediate results rather than revising the plan. o1's test-time compute enables explicit backtracking \(Monte-Carlo Tree Search in latent space\). The cost crossover point is around 4 tool calls: below this, o1's overhead dominates; above it, GPT-4o's error rate creates exponential retry costs and infinite loops. The signature for upgrade is failure rate >20% on 3-step plans.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-06-21T22:19:27.900720+00:00— report_created — created