The document provides an overview of tools for monitoring and troubleshooting GlassFish application servers, including command line tools like jps, jstat, jmap, jstack, asadmin, graphical tools like the GlassFish Admin Console and VisualVM, and more advanced tools like Memory Analyzer, Oracle JRockit, the Attach API, instrumentation, and BTrace. It describes example uses like identifying memory leaks, monitoring thread activity, and dynamically injecting tracing scripts into a running JVM.