The same tooling that you'd use. AI is not magic, it cannot know exactly how a program will run under your exact circumstances and data. Therefore, if it can use a profiler, test suite or application, or be able to read logs, just like you would, it then can make changes, evaluate them, and iterate. Personally, I've created test MCP servers that will perform actions like submit orders, have the AI capture and analyze PerfViews and Concurrency Visualizer, write out tracing data to logs... all the same stuff I was doing by hand for years.