Concepts

How AI Agents Work: The Loop Explained Step by Step

A conceptual walkthrough of how AI agents work: input and context, reasoning and planning, tool selection, execution, observation and iteration.

August 17, 2026 11 min readBy the WKIL team

The short answer

An AI agent works through a repeating loop, not a single response. It takes an input plus context (instructions, knowledge, prior conversation), reasons about the next step, picks a tool if it needs to act outside itself, executes, observes the result, then decides: loop again, stop because the goal is met, or ask a human before continuing a sensitive step.

The loop, step by step

1) Perception and input

The starting point: a message, an event, or a scheduled trigger. This is what kicks off the loop.

2) Context

Before reasoning, the agent is given context: role instructions, relevant knowledge from a knowledge base, and prior conversation history if any. Missing context is the most common cause of weak decisions.

3) Reasoning and planning

The agent evaluates the gap between the current state and the goal, and picks the next step that closes it. This evaluation repeats after every step, not just once at the start.

4) Tool selection

If the next step requires action beyond generating text — reading a record, sending an email, updating a status — the agent selects the right tool from a predefined toolset.

5) Execution

The tool is actually called with the parameters the planning step decided on.

6) Observation

The agent inspects the result of execution: did it succeed, fail, or return unexpected data? This observation feeds the next planning pass.

7) Iteration or stopping

Based on the observation, the agent decides: take another step, finish because the goal is met, or stop to ask for human approval at a sensitive or ambiguous point.

PerceivePlanActObserveLearnContinuous feedback
The AI agent operating loop

Loop stages table

StageQuestion it answersExample
PerceptionWhat just happened?A new customer message arrived
ContextWhat do I know about this situation?Refund policy plus order history
ReasoningWhat is the next step?Check shipment status before replying
Tool selectionWhich tool performs this step?A shipment tracking tool
ExecutionWhat actually happened?The tool was called and returned a status
ObservationIs the result enough?Status: delayed — needs another decision

The role of memory and context

Memory is what connects one loop to the next across time: remembering a customer already complained, or that a ticket was escalated before. Without it, an agent re-asks the same questions every time. Context often comes from a knowledge base, and wiring an agent to one closely resembles retrieval in RAG-style systems (retrieval-augmented generation).

When an agent stops

  • The stated goal for the task is met.
  • A maximum number of steps or time budget is reached.
  • It hits an irreversible action and requests human approval.
  • It hits ambiguity it cannot resolve from available context.

Limitations of this model

This is a conceptual walkthrough of the loop, not a build guide. Turning this loop into an actual agent on WKIL means translating it into instructions, knowledge, tools and approval points configured in practice — that is what the how-it-works page covers, not this article.

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