Home Speakers Simon Willison Quote This turns out to be the big unlock: the latest coding agents against the ~November 2025 frontier models are remarkably effective if you can give them an existing test suite to work against.
Words found on the source page on Nov 6, 2026.
More from Simon Willison Blog Conceptual integrity and counting lines of code Aug 19, 2026
I can churn out code a hundred times faster. I don’t have the cognitive capacity to stay on top of 100 times the amount of code. So you still need a team of engineers, so you can load balance that cognitive capacity across the team. Blog Conceptual integrity and counting lines of code Aug 19, 2026
I can do way more work as a single engineer than I could without agents. Blog Conceptual integrity and counting lines of code Aug 19, 2026
It used to be that the discipline was enforced on you by the amount of time it took. Blog Conceptual integrity and counting lines of code Aug 19, 2026
That’s exactly the problem with coding agents and software: it’s very easy to keep adding new rooms, because the cost of adding those rooms is so much cheaper. Blog 2025: The year in LLMs Dec 31, 2025
A prompt injection attack against a browsing agent that can exfiltrate or modify that data is a terrifying prospect. Blog 2025: The year in LLMs Dec 31, 2025
But if you define agents as LLM systems that can perform useful work via tool calls over multiple steps then agents are here and they are proving to be extraordinarily useful. Blog 2025: The year in LLMs Dec 31, 2025
Claude Code and friends have conclusively demonstrated that developers will embrace LLMs on the command line, given powerful enough models and the right harness. Blog 2025: The year in LLMs Dec 31, 2025
I think that’s a waste of a great term, especially since it’s becoming clear likely that most programming will involve some level of AI-assistance in the near future. Blog 2025: The year in LLMs Dec 31, 2025
The most impactful event of 2025 happened in February, with the quiet release of Claude Code. Blog 2025: The year in LLMs Dec 31, 2025
The reason I think MCP may be a one-year wonder is the stratospheric growth of coding agents.
On the same topics Blog Will agents have network effects? Oct 6, 2026
If the content creation loop works for agentic virality, I think it means there’s a big incentive for every agent to volunteer to make visually-appealing, shareable content, do this often. Blog Thinking in Systems, Shipping in Loops Sep 24, 2026
AI has removed the typing from software engineering & left the system design. Blog Thinking in Systems, Shipping in Loops Sep 24, 2026
The craft of fitting code together by hand is over; what remains is designing the loop that decides whether the output is right. Blog Thinking in Systems, Shipping in Loops Sep 24, 2026
This is the new software engineering: designing the systems that let AI write code correctly at scale. Talk Speech at the UN Security Council Sep 23, 2026
I address you today at a moment of global awakening: in recent months, AI agents developed by leading companies have acted in unacceptably dangerous ways, against instructions. Blog Frontier Overhangs Sep 21, 2026
Once you have put all of your information into a personal agent and actually incorporated it into your day-to-day life, it is much more of a challenge to change to something else. About this quote 
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