What is an AI agent?
Definition
An AI agent is a software system in which a large language model (LLM) decides, step by step, what to do next and which tools to use until a task is done. Anthropic describes agents as "systems where LLMs dynamically direct their own processes and tool usage, maintaining control over how they accomplish tasks."
Checked: 2026-10-29 (Beijing time) · Sources
Agent or workflow?
Anthropic groups both under the name "agentic systems" but draws a line between them. Workflows are "systems where LLMs and tools are orchestrated through predefined code paths". Agents choose their own path. Anthropic calls the basic building block an "augmented LLM": a model enhanced with retrieval, tools and memory.
Anthropic's post was published on Dec 19, 2024, and the page itself now says that much of the tooling it describes has changed since then. The workflow-versus-agent distinction is still the clearest short definition we found.
Examples
- Workflow, not an agent: a fixed automation built in a tool such as n8n or Zapier: new form entry → an LLM summarizes it → the summary is posted to a chat channel. The steps never change.
- Agent: a coding agent such as Claude Code given "fix the failing test". Anthropic's docs describe it as an agentic coding tool that reads your codebase, edits files and runs commands, so it decides which files to open and what to run until the job is done. On this site we call this kind of tool a coding agent.
To build a small agent yourself, start with our tool-calls agent prompt. Before you trust an agent's code changes, see AI code review.
Related tools on this site
- n8n: Fair-code workflow automation platform with native AI: visual building plus custom code, self-host or cloud, 400+ integrations.
- Zapier: No-code automation across thousands of apps, plus AI agents and chatbots.
- CrewAI: Framework for orchestrating role-playing, autonomous AI agents that collaborate on complex tasks; commercial platform available.
- LangGraph: Open-source framework from LangChain for building resilient, stateful agents.
- Browser Use: Open-source Python library for AI browser agents, plus Browser Use Cloud with stealth browsers and a hosted agent API.
- Claude Code: Anthropic's agentic coding tool: understands your codebase, edits files, runs commands in the terminal or IDE.
- Cursor: AI coding agent and editor: hand off coding tasks to agents that turn ideas into code.
Related pages
- Best AI agents for automation
- Prompt: build a simple AI agent with tool calls
- Best AI for vibe coding
- All glossary terms
Sources
- Anthropic Engineering: Building effective agents (published Dec 19, 2024). Checked: 2026-10-29.
- Claude Code docs: Overview. Checked: 2026-10-29.
We only state facts we checked on the linked sources on the dates shown. Found a mistake? Email jazz.fanpeng@mail.grokbot.com.