From answering to acting

AI Agents and Tool Use

An agent can plan, browse, call tools and perform tasks. That changes website design from information retrieval alone to safe, machine-operable interaction.

Published 2026-07-22Last reviewed 2026-07-22Primary-source analysis
Definition

A system with goals, tools and action loops

An AI agent is a system that can interpret a goal, decide on intermediate steps, call tools or services, observe results and continue until it reaches a stopping condition. The degree of autonomy varies widely.

A browser agent may navigate a site, complete a form or initiate a transaction. A support agent may query a knowledge base and create a ticket. An internal agent may combine documents, databases and approval workflows.

The agent loop

Plan, act, observe and verify

  1. Interpret the user’s objective and constraints.
  2. Select a tool, page, API or action.
  3. Perform a bounded operation.
  4. Read the result and update the plan.
  5. Request confirmation before a consequential commitment.
  6. Stop, escalate or recover when the environment is ambiguous.
Website requirements

Accessible interfaces become operational infrastructure

OpenAI advises publishers and developers that accessible page structure and ARIA labels can help agents interpret interactive elements. W3C guidance begins with native semantic controls and adds ARIA when the host language does not express the needed role or state.

Agent risk

A successful click is not necessarily authorized success

Ambiguous intent

The agent chooses an action that the user did not mean.

Hidden condition

A fee, renewal or restriction is not visible before confirmation.

Prompt injection

Content attempts to redirect the agent away from the user’s objective.

Identity error

The agent acts on the wrong account, product or organization.

Permission error

The tool exposes information or capabilities beyond the user’s authorization.

Recovery failure

The interface does not explain whether the action completed or how to reverse it.

Measurement

Evaluate task completion with safety

Agent performance should be measured through successful authorized completion, confirmation quality, error recovery, escalation and policy compliance—not simply the number of actions performed.

Source trail

Primary material behind this analysis

OECD Explanation of the Updated Definition of an AI System

A practical distinction among AI systems, models, inputs, inference, outputs, autonomy and adaptiveness.

Open the original source at OECD.AI →

Related reading

Continue through the discovery stack

OECD Definition of an AI System

An explanation of the OECD AI-system definition and the differences among models, complete systems, inputs, inference, outputs, autonomy and adaptiveness.