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AI Agents Explained: What They Do and Where They Fail

AI agents are systems in which a language model decides its own steps and uses tools, such as search, files, or software actions, in a loop until a task is done. That autonomy is useful for open-ended tasks but adds cost, delay, and the risk of compounding mistakes, so most experts advise starting with the simplest approach that works and keeping a human in charge of high-risk actions.

Last reviewed: October 2026.

AI agents explained: a language model planning steps and using tools in a loop

“AI agents” is one of the most overused phrases in technology right now. This guide separates the meaning from the marketing: what an agent is, how it differs from a chatbot or a fixed automation, where agents genuinely help, what can go wrong, and how to evaluate a product or try one yourself. It is for non-specialists, small business owners, and anyone deciding whether an “agentic” tool is worth using. We draw on Anthropic's engineering guidance, the OWASP project's security guidance, and a Gartner analysis of the market.

Chatbot, workflow, or agent: the practical difference

Anthropic's engineering team draws a useful line. In a workflow, language models and tools follow code paths that a developer defined in advance. In an agent, the model itself chooses its steps and which tools to use, typically running a loop: call a tool, check the result from the environment, and repeat until the task finishes or a stopping condition such as a maximum number of iterations is reached.

TypeWho decides the stepsTypical example
ChatbotYou, one message at a timeAsking a question and getting an answer
WorkflowA developer, in advanceSummarize each new email, then file it by category
AgentThe model, step by stepResearch a topic, open sources, compare them, and draft a report

Many products labeled “agents” are really workflows, and that is not a criticism. Predictable steps are often what you want.

How AI agents actually work

  1. Goal. You describe the outcome you want.
  2. Plan. The model decides on a next step.
  3. Act. It calls a tool: a search, a spreadsheet, a calendar, a code runner.
  4. Observe. It reads the result and updates its approach.
  5. Repeat or stop. It continues until done, blocked, or out of budget.

The quality of the tools matters as much as the model. Anthropic's guidance says to invest as much in tool design as in prompts, and gives an example where requiring absolute file paths eliminated errors that appeared once an agent changed directories.

Because the loop can run many times, it needs boundaries. Sensible limits include a maximum number of steps, a spending cap, a list of allowed tools, and clear points where the agent must stop and ask you. Anthropic's guidance also stresses keeping designs simple and making the agent's planning steps visible, which helps you understand why it did what it did and fix it when it goes wrong.

Where agents help, and where simpler tools win

Anthropic advises starting with the simplest solution, noting that a single model call with retrieval and examples is often enough. It recommends workflows for well-defined tasks where predictability matters, and agents for open-ended problems where the number of steps cannot be predicted or hardcoded and where you can trust the model's decisions at scale.

  • Good fits: multi-step research, software changes spanning several files, and tasks with clear success checks.
  • Poor fits: anything where a mistake is expensive and cannot be undone, tasks with vague goals, and jobs a fixed script handles perfectly well.

The real costs: money, time, and compounding errors

Anthropic notes that agentic systems often trade latency and cost for better task performance, and that their autonomy raises costs and can compound errors across steps. A small misunderstanding in step two can steer steps three to ten in the wrong direction. Its recommended mitigations are extensive testing in sandboxed environments and suitable guardrails.

Energy is part of the picture too. The International Energy Agency has said agentic and reasoning tasks can use hundreds to thousands of times more energy per query than a simple text request; our article on sustainable AI infrastructure covers the numbers.

Security: prompt injection is the central risk

OWASP's guidance on large language model risks defines prompt injection as input that changes a model's behavior in unintended ways. In indirect prompt injection, the model reads external content, such as a web page or file, containing instructions that alter its behavior. For an agent that browses the web or reads your email, that means a malicious page could try to steer it.

OWASP lists mitigations that reduce impact, including least-privilege access, requiring human approval for high-risk actions, clearly separating and labeling untrusted external content, validating outputs with deterministic code, and regular adversarial testing. It also states that no foolproof prevention method is currently known. Practically: do not give an agent more access than the task needs, and do not let it send money, delete data, or message people without your approval. The privacy side is covered in our guide to AI data privacy.

How to spot agent washing

In June 2025, Gartner predicted that more than 40% of agentic AI projects would be shut down by the end of 2027 because of rising costs, unclear business value, or insufficient risk controls. It also described “agent washing,” where vendors rebrand assistants, robotic process automation, or chatbots as agentic AI, and estimated that only about 130 of the thousands of vendors claiming agentic products were genuine. That is a forecast, not a measurement, but it matches common sense: ask for specifics.

  • What decisions does the system make on its own?
  • Which tools and data can it access, and can you limit them?
  • Where is a human approval required?
  • How is quality measured, and can you see a log of its actions?
  • What does a failed run cost?

How to try AI agents safely

  1. Pick a low-stakes task, such as gathering sources or drafting a first outline.
  2. Give read-only access first and add write access only if needed.
  3. Set budget and time limits.
  4. Review the action log and verify any important output yourself.
  5. Keep sensitive accounts and credentials out of scope until you trust the setup.

Agents are also being applied in research, for example in labs that plan experiments; see our look at AI for materials science for a grounded example.

What AI agents mean for you

  • Individuals: use agents for drafts, research, and chores where you will check the result.
  • Small businesses: begin with a predictable workflow and graduate to an agent only where flexibility is truly needed.
  • Buyers: insist on logs, permission controls, and a trial on real but low-risk tasks.
  • Everyone: remember that fluent output is not proof of correct output.

Worked example: what AI agents do with a real task

Abstract definitions only go so far. Therefore, here is an illustrative example of how AI agents handle an everyday job. Imagine you ask one to prepare a short competitor summary for a small coffee roaster.

  1. Goal. You write: find the five closest specialty roasters, note their bestsellers and opening hours, and draft a one-page comparison.
  2. Plan. The model decides to search maps first, then open each roaster website, then write the summary.
  3. Act and observe. It runs the map search, reads the results, and notices one listing is a chain rather than a roaster. As a result, it drops that entry and searches again.
  4. Loop. It opens five websites in turn, records the details it finds, and flags one site where the hours were missing.
  5. Stop. It writes the comparison, lists the missing data, and hands the draft back to you for review.

Why the review step matters

Notice two things. First, the agent made several decisions you never specified, which is the whole point. Second, each decision was a chance to go wrong. For example, if it had misread the map results, every later step would have been built on bad data. This is why a review step at the end is not optional.

In this example, a fixed workflow could have done the job almost as well, because the task shape was predictable. AI agents earn their keep when the steps cannot be planned in advance, such as debugging software or tracing a complex question across many sources.

Common misconceptions about AI agents

Because the term is used loosely, a few myths keep circulating. Clearing them up helps you judge products and set realistic expectations.

  • Myth: AI agents understand your goals. They infer goals from text. Consequently, vague instructions produce vague or surprising results. Be explicit about what done means and what is off limits.
  • Myth: more autonomy is always better. In practice, the most reliable deployments keep the autonomous loop small and put humans at the points where mistakes are costly.
  • Myth: an agent that writes confidently is correct. Fluency and accuracy are separate properties. An agent can describe a step it never completed, so check logs rather than summaries.
  • Myth: AI agents remember everything. Most have a limited working context. Long tasks can push early instructions out of view unless the system is designed to store and re-read them.
  • Myth: agents replace whole jobs. They currently replace tasks within jobs, usually the repetitive, well-bounded ones. The judgment parts still sit with people.

A checklist before you hand work to AI agents

Before letting AI agents touch anything that matters, run through this short list. It takes a few minutes and prevents most of the expensive failures described earlier.

  1. Define success in one sentence. If you cannot state what a correct result looks like, the agent cannot either.
  2. List what it may touch. Name the folders, accounts, and tools in scope. Everything else stays out, especially payments, deletions, and outbound messages.
  3. Set a budget. Decide the maximum steps, time, or spend you will accept for a single run. Many platforms let you configure this directly.
  4. Choose a reversible first task. Drafting, summarising, and research are easy to undo. Sending and purchasing are not.
  5. Decide who reviews the output. Assign a person, not a second model, for anything that reaches customers or regulators.
  6. Keep the log. Save the action trail from each run. It is your only reliable record of what happened when something goes wrong.

Teams that follow this routine typically find that AI agents are useful for a narrower set of tasks than the marketing suggests, but genuinely useful for those. That is a good outcome. Moreover, the discipline of writing down scope and success criteria tends to improve how people delegate to each other, not just to software.

Sources and further reading

Frequently asked questions

What is an AI agent?

An AI agent is a system where a language model chooses its own steps and uses tools in a loop to complete a task, as opposed to following a fixed script.

How is an agent different from a chatbot?

A chatbot responds to each message you send. An agent can plan multiple steps, call tools, check results, and continue without you directing each move.

What is the difference between a workflow and an agent?

In a workflow, a developer predefines the steps. In an agent, the model decides the steps and tool use at runtime.

Are AI agents reliable enough to trust?

Not blindly. Autonomy can compound errors across steps, so test in low-stakes settings, limit permissions, and review important outputs.

More questions about AI agents

What is prompt injection?

It is when input, often hidden in a web page or file, changes an AI model's behavior in unintended ways. OWASP says no foolproof prevention is currently known, so least privilege and human approval matter.

What is agent washing?

Gartner uses the term for vendors rebranding chatbots, assistants, or robotic process automation as agentic AI without substantial agentic capability.

Do agents use more energy?

The IEA says agentic and reasoning tasks can use hundreds to thousands of times more energy per query than a simple text request.

Should my business use an AI agent?

Start with the simplest approach that works. Use an agent only for open-ended tasks where the steps cannot be predicted, and keep humans approving high-risk actions.

Who should not use AI agents yet?

Anyone whose task involves irreversible actions, such as sending money, deleting records, or contacting customers, should hold off unless the platform supports approval steps and detailed logs. A fixed workflow or a plain assistant is safer for those jobs.

What tools do AI agents typically use?

Common tools include web search, web browsing, file reading and writing, code execution, calendars, email, and company databases. Each tool widens what the agent can do and also what it can get wrong, so grant them one at a time.

How do I know whether a product is really an agent?

Ask what decisions the system makes on its own, whether it can call tools in a loop, and whether you can see a step-by-step log. If the vendor cannot answer those questions clearly, treat it as an assistant or a workflow rather than an agent.

Disclaimer: This article provides general information only and is not technical, legal, or business advice. The field changes quickly, and forecasts cited are estimates. Check current documentation and consult qualified professionals for important decisions.

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