Agentic AI interview question · Agent foundations · junior level
Describe the basic agent loop.
Free to read in full. This is 1 of the 120 questions in the Agentic AI Engineering interview pack, with 153 diagrams. Get the pack, ₹999 · $20
Why it is asked
Checks that you understand the core mechanism every agent framework implements, including how it ends.
The answer
The agent loop repeats four steps: the model reads the current context, decides on an action (call a tool or give a final answer), your code runs the tool, and the result is added to the context for the next turn.
The context is all the text the model reads in one call. Text is counted in tokens, small pieces of words; 100 tokens is roughly 75 English words.
In more detail:
1. Build the context: system instructions, the user's goal, the tool definitions, and everything that has happened so far (earlier tool calls and their results). 2. Call the model. It returns either a tool call, for example search_orders(customer_id="C42"), or a final answer. 3. If it is a tool call, your code checks it, runs the tool, and captures the result or the error. 4. Append the tool call and its result to the context, then go back to step 2.
The loop ends when the model gives a final answer, or when a limit you set is reached: a maximum number of steps, a token or money budget, a time limit, or a human stopping it. Those limits are not optional; without them a confused agent can loop for a long time.
Two details matter in practice. The context grows every turn, so cost and latency grow too, which is why long tasks need summarizing or trimming. And the model never runs anything itself: your code is in control of every action, which is where you add checks and approvals.
What the interviewer listens for
- Context in, decision out: tool call or final answer
- Your code executes tools and appends results
- Stops on final answer or on step, budget or time limits
- Context grows each turn, raising cost and latency
Follow-ups the interviewer may ask
- Where do you add a human approval? Hint: between the model's tool call and your code executing it.
- What happens to errors? Hint: return them to the model as the tool result so it can try another way.
Common mistakes
- Describing the loop without any stop condition
- Saying the model executes the tools
Written by Roni Das, who builds distributed systems and AI systems for a living.
Learn it properly
This is taught step by step in the course lesson The Agent Loop: Why AI Agents Fail as Tasks Get Longer, which is free to read.
One question is not enough for the interview.
This is 1 of the 120 questions in the Agentic AI Engineering pack
Each question has why it is asked, a full answer, what the interviewer listens for, the follow-ups, the common mistakes and a diagram (153 diagrams in all). A PDF you keep, junior to staff level.
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