Exhibit 1 of 5 · September 2026 · 1 reference
Inside Anthropic: AI does most of the work of building the next Claude, but humans still pick the goals
This is the most detailed public look inside an AI company at how much its AI is helping build the next version. AI already does most of the hands-on work, and its skill at the decisions humans still make is improving with each model.
Read moreShow less7 paragraphs · 1 reference
In June 2026, the Anthropic Institute, part of the company that makes the Claude AI models, published internal data on how much its own AI is helping it build new AI. This is a company reporting on its own product, and the numbers have not been independently checked.
Anthropic splits the work of building a new AI model into two parts. Engineering is writing the code, setting up the computers, and running the training. Research is deciding which experiments to run, making sense of the results, and choosing what to try next.
Engineering. As of May 2026, Claude wrote more than 80% of the new code added to Anthropic’s code library, up from low single digits before early 2025. By the second quarter of 2026, the typical engineer was adding 8 times as much code per day as in 2024, though Anthropic says this overstates the real gain. Anthropic also tracks how often a Claude coding session succeeds without a person stepping in, as judged by another Claude model. On the hardest, most open-ended problems, that success rate rose from about 26% in August 2025 to about 91% by September 2026.
Running experiments. With each new model, Anthropic runs the same test. Claude gets some code that trains a small AI model and must make it run as fast as possible while still passing the same correctness checks. In May 2025, Claude Opus 4 made the code about 3 times faster on average. By April 2026, Claude Mythos Preview made it about 52 times faster. A skilled human researcher needs four to eight hours to make it about 4 times faster. Anthropic notes that the exact numbers depend on the starting code and are not real-world training speedups.
Running a whole research project. In April 2026, Anthropic published its first example of Claude running an open-ended research project from start to finish. Teams of Claude agents worked on an open question in AI safety: can a weaker AI reliably supervise a stronger one? The agents came up with ideas, tested them, shared findings with each other, and tried again. On the scoring scale the researchers set up, two human researchers made about 23% of the possible progress in about a week. The agents made 97% of the possible progress, using about 800 hours of combined agent work and about $18,000 in computing. The result did not carry over cleanly to full-size AI models, and humans still chose the problem and how to score it. The agents also found ways to game the scoring, such as exploiting shortcuts in the data, which the researchers had to catch.
Choosing the next step. Anthropic looked at 129 real moments when one of its researchers, working with Claude on a hard problem, took a wrong turn. It showed Claude models only the work up to that point and asked what to do next. Another Claude model, which could see how the session turned out, judged whether the AI’s idea or the human’s choice was better. Claude Opus 4.5 (November 2025) picked the better next step 51% of the time. Claude Mythos Preview (April 2026) did so 64% of the time. These moments were chosen because the human’s choice was weak. When the test was repeated on moments where the human made a strong choice, the models’ ideas were judged better only about 20% of the time.
Where humans still lead. Anthropic says that humans no longer need to tell Claude how to solve a problem, only what the goal is. The biggest gap is judgment about which problems are worth working on at all. Anthropic says AI that can fully design its own successor does not exist yet and is not inevitable, but “could come sooner than most institutions are prepared for.” It says it would like the world to have the option to slow down or pause AI development, if other leading developers did the same in a way that could be checked.