I need to put one together. The big ones are:
- "LLM running tools in a loop" - often used by Anthropic, generally the most popular among software engineers who build things
- "An AI system that performs tasks on your behalf" - used by OpenAI, I dislike how vague this one is
- "an entity that perceives its environment through sensors and acts upon that environment through actuators to achieve specific goals" - the classic academic one, Russell and Norvig. I sometimes call this the "thermostat definition".
- "kinda like a travel agent I guess?" - quite common among less technical people I've talked to
I gathered over a hundred on Twitter last year, summarized by Gemini here: https://gist.github.com/simonw/beaa5f90133b30724c5cc1c4008d0...
I also have a tag about this on my blog: https://simonwillison.net/tags/agent-definitions/