(2025-09-18) Willison I Think Agent May Finally Have A Widely Enough Agreed Upon Definition To Be Useful Jargon Now

Simon Willison: I think “agent” may finally have a widely enough agreed upon definition to be useful jargon now. (coding agent)

when I talk about agents I’m going to use this:
An LLM agent runs tools in a loop to achieve a goal. (AI-agent)

I’ve been very hesitant to use the term “agent” for meaningful communication over the last couple of years. It felt to me like the ultimate in buzzword bingo—everyone was talking about agents, but if you quizzed them everyone seemed to hold a different mental model of what they actually were.

Jargon terms are only useful if you can be confident that the people you are talking to share the same definition! If they don’t then communication becomes less effective—you can waste time passionately discussing entirely different concepts.

An LLM agent runs tools in a loop to achieve a goal. Let’s break that down.

The “tools in a loop” definition has been popular for a while—Anthropic in particular have settled on that one. This is the pattern baked into many LLM APIs as tools or function calls—the LLM is given the ability to request actions to be executed by its harness, and the outcome of those tools is fed back into the model so it can continue to reason through and solve the given problem.

“To achieve a goal” reflects that these are not infinite loops—there is a stopping condition.

Agents as human replacements is my least favorite definition

This often takes the form of “customer support agents”, but you’ll also see cases where people assume that there should be marketing agents, sales agents, accounting agents and more.

If someone surveys Fortune 500s about their “agent strategy” there’s a good chance that’s what is being implied. Good luck getting a clear, distinct answer from them to the question “what is an agent?” though!

there’s one key feature that remains unique to human staff: accountability.

OpenAI need to get their story straight

The single biggest source of agent definition confusion I’m aware of is OpenAI themselves. OpenAI CEO Sam Altman is fond of calling agents “AI systems that can do work for you independently”.

Back in July OpenAI launched a product feature called “ChatGPT agent” which is actually a browser automation system—toggle that option on in ChatGPT and it can launch a real web browser and use it to interact with web pages directly.

There’s already a meme for this

Josh Bickett tweeted this in November 2023: