Last reviewed:
What is the agentic loop? Definition and pitfall to avoid
The agentic loop is the iterative cycle of an AI agent that acts, observes the result, and decides on the next action, until it reaches its goal or a stopping criterion. Without limits or observability, it can diverge into an infinite loop and consume in a few minutes the equivalent of several days of normal use.
A typical agentic loop chains four phases. Thought: the model reflects on the next step. Action: it invokes a tool. Observation: it receives the result. Decision: it evaluates whether the goal is reached or continues. This structure, inspired by the ReAct paradigm (Yao et al., 2022), is the basis of most agents in production. Three structural risks lurk in any agentic loop. Infinite loop: the agent does not find a stopping criterion and continues indefinitely. Cost drift: each iteration consumes tokens, and a poorly framed agent can multiply consumption by one hundred. Error cascade: an error at step N pollutes all subsequent steps, the agent correcting errors on false premises. Mature deployments impose systematic ceilings: maximum number of iterations, token budget, absolute timeout.
Concrete example
Illustrative case. An 80-employee SaaS vendor deploys a technical support agent in June 2025. During a poorly framed update, the agent enters a loop on tickets open for more than 90 days without having a closure criterion. In one night, the agent performs 14,000 iterations on 230 tickets, consuming 8 million tokens, for a cost of 1,100 euros instead of 12 euros on a normal day. The bug is detected in the morning by the API budget monitoring. Fix: ceiling of 5 iterations per ticket, systematic escalation to a human beyond, mandatory audit log. Since then, no similar incident in 11 months.
FAQ
What is the agentic loop?
It is the iterative cycle of an AI agent that acts, observes the result, then decides on the next action, until it reaches its goal or a stopping criterion. A typical loop chains four phases: thought, action, observation, decision.
Why can an agentic loop drift out of control financially?
Each iteration consumes tokens. Without a stopping criterion, the agent can run in an infinite loop and, in a few minutes, consume the equivalent of several days of normal use. Illustrative case: a support agent could run 14,000 iterations in one night and cost 1,100 euros, against 12 euros on a normal day.
What is the error cascade?
An error made at step N pollutes every subsequent step: the agent keeps correcting errors on premises that are already false. It is one of the three structural risks of any agentic loop, alongside the infinite loop and cost drift.
What guardrails should you set before putting an agent into production?
Three non-negotiable measures: an explicit ceiling on iterations per session (typically 5 to 20) with automatic escalation to a human beyond it, a blocking token budget per session, and granular observability where every thought, action and observation is logged. The real pitfall is not the model's incompetence, it is the absence of guardrails around the loop.
Why is observability indispensable?
Without a timestamped, inspectable log of every step, diagnosing an incident becomes impossible. That is why 89% of respondents to LangChain's survey (late 2025) had implemented agent observability, and 94% of those with agents in production.
See also
Further reading
ReAct: Synergizing Reasoning and Acting in Language Models, Yao et al., 2022
Sources
- ReAct: Synergizing Reasoning and Acting in Language Models, Yao et al., arXiv:2210.03629, 2022. https://arxiv.org/abs/2210.03629
- State of Agent Engineering 2026, LangChain (89% of respondents, Nov-Dec 2025 survey, 1,340 responses). https://www.langchain.com/state-of-agent-engineering