Aspects of the subject matter described herein relate to assisting development tools. In aspects, statements that influence runtime behavior may be inserted into code of a program. For example, a statement inserted into a function may set a property of a runtime object to indicate that a debugger is to be notified for exceptions that are encountered within the scope of the function. When a runtime environment encounters an exception, the runtime environment may determine whether the property applies to the currently-executing scope. If so, the runtime environment may notify or not notify a development tool of the exception based on the value of the property.