The phrase "AI agent" has been thrown around so much in the last few years that it has almost lost meaning. So let's narrow it down. A surrogate AI agent is a piece of software that acts on your behalf to accomplish a goal — not just answer a question, but actually take steps in the world, make decisions, and report back when it is done.
From chatbot to agent
A chatbot responds to one message at a time. An agent runs a loop: it observes the state of the world, decides what to do next, takes an action, and observes again. That loop is the core of every modern agent framework, from AutoGPT to LangGraph to OpenAI's Assistants API.
What turns an agent into a surrogate agent is the delegation contract. You give the agent:
- a goal ("book me a flight to Lisbon under 200 EUR for next weekend"),
- a set of tools it is allowed to use (browser, email, calendar, payment method),
- and constraints ("never spend more than 250 EUR without asking").
Then you walk away. The agent runs until it either finishes the goal or hits a constraint that requires your input.
Why surrogate agents are different
Most software waits for you. A surrogate agent does not. It runs while you sleep, it batches dozens of small tasks you would never bother to do manually, and it picks up patterns you would not notice. The shift is roughly the same as the shift from "I write every email" to "my assistant handles the routine ones."
What makes them work in practice
After building a handful of these systems, three things matter more than the model you pick:
- Tool design. A well-named tool with a tight JSON schema beats a clever prompt every time. If the agent has to guess what
fetch_data(scope)means, it will guess wrong. - Memory. Short-term context (this run) and long-term memory (your preferences) need to live in different places. Cramming both into the prompt is the single biggest source of weird behaviour.
- Stop conditions. Most failed agents do not fail because they are dumb. They fail because nobody told them when to stop trying.
Where this goes next
The interesting frontier is not bigger models — it is fleets of small, specialised surrogate agents that hand work to each other. One watches your inbox, one drafts replies, one books meetings, one writes the weekly summary. None of them are general intelligence. Together they replace a junior assistant.
That is roughly the bet behind everything I am building on this site. If that resonates, the rest of the posts here go deeper into how to actually ship one of these things.