Writing a basic recipe
The user will need to write a basic recipe to be able to run their own personal diagnostic. An example of such a recipe is found in esmvaltool/recipes/recipe_my_personal_diagnostic.yml. For general guidelines with regards to ESMValTool recipes please consult the User Guide; the specific parameters needed by a recipe that runs a personal diagnostic are:
scripts: my_diagnostic: script: /path/to/your/my_little_diagnostic.py
i.e. the full path to the personal diagnostic that the user needs to run.
There is also a lesson available in the ESMValTool tutorial that describes in a step-by-step procedure how to write your own recipe. It can be found here.