Add brief tool packages descriptions

doc/design_ros_2.md

@@ -551,6 +551,33 @@ We could look into making analyses work on both ROS 1 and ROS 2, through a commo
 
 ## Tools
 
+* `tracetools_trace`
+    * wraps the LTTng Python bindings to setup and start a tracing session
+    * exposes simplified setup functions with default values
+    * provides an example `trace` entrypoint for tracing
+        ```shell
+        $ ros2 run tracetools_trace trace
+        ```
+* `ros2trace`
+    * provides a `ros2cli` extension
+        * uses `tracetools_trace` functions
+* `tracetools_launch`
+    * provides a `Trace` action for `launch`
+        * uses `tracetools_trace` functions
+* `tracetools_read`
+    * wraps the `babeltrace` Python bindings to read CTF traces
+* `tracetools_test`
+    * provides a `TraceTestCase` class extending `unittest.TestCase`
+        * uses the `Trace` action with `launch` to trace the test nodes
+        * provides utility functions (e.g. assertion)
+
+* `tracetools_analysis`
+    * uses `tracetools_read` to read traces
+    * provides utilities to:
+        * convert CTF traces to pickle files
+        * wrap trace events in a Python `dict`
+        * handle and process trace events to gather data
+
 ## Analysis architecture
 
 With profiling as an example implementation.