AI Agent
An AI agent is a system that does not just answer questions but takes actions to get things done. Given a goal, it can plan a series of steps, use tools such as a web browser, a calendar, or another piece of software, check its own progress, and carry on until the task is complete. The shift is from an assistant that tells you how to do something to one that goes and does it for you.
A standard chatbot is reactive: you ask, it replies, and there it stops. An AI agent is built to be proactive and persistent. Suppose you ask it to organise a team lunch. Rather than simply suggesting how you might do it, an agent could check everyone’s calendars, find a suitable time, search for nearby restaurants, make a booking, and send out the invitations, all through a chain of its own decisions and actions. It breaks a broad goal into steps and works through them.
The engine driving most agents is a large language model, which supplies the reasoning to plan and adapt. What turns that reasoning into an agent is access to tools and the freedom to use them in a loop: try something, observe the result, decide what to do next, and repeat until the job is done or it needs to check in. This loop of thinking and acting is what people mean when they describe a system as agentic.
Agents are one of the most talked about frontiers in AI, and for good reason. Done well, they promise to automate genuinely useful multi-step work, from software development to research and administration. But handing a system the power to act, rather than just advise, raises the stakes considerably: mistakes have real consequences, and questions of oversight, permissions, and trust become pressing. Many of the UK startups we cover are racing to build agents that are capable enough to be useful and constrained enough to be safe.
Related terms
Articles using this term
- CloudNC raises $20M to point AI at the factory floor 10 September 2026
- Embedd raises £2M to be the software glue for physical AI 1 September 2026
- Prevalent AI raises $22M — nine years in, and profitable 30 August 2026
- Sqwish raises £1.7M to squeeze the cost out of running AI 27 August 2026
- UK AI Security Institute finds agents going off-script in cyber tests 13 August 2026
- Cytix raises £5.1M to manage the security risk of AI-written code 12 August 2026
- Agon raises £22.5M to train defence AI in synthetic battlefields 29 July 2026
- Dwelly raises £128M to buy up UK letting agencies and run them on AI 28 July 2026
- UK AI Security Institute launches Control Red Team, finds flaws in every safety monitor it tested at Anthropic and DeepMind 24 July 2026
- NHS England expands AI across triage, notes, and staff tools 4 July 2026