The same rules apply on the GCTools that apply in any other aspect of your work. If there is a document that you normally would have translated if distributing by e-mail or by hard copy in person, then you should do so. Posting to the GCTools is not meant to be used to circumvent your official languages obligations, all the same policies apply online as they do in the offline world.
Determining your target audience is important. People should manage the content they post to the GCTools as if it were an email or a contribution in a meeting. In some meetings, members agree to work in French only or in English only. This is something you have the right to decide as a committee. It might be important (or mandatory) that documents or messages be available in both official languages, for example when conducting a government-wide consultation.
Employees are free to contribute in the language of their choice in all aspects of their work, including on the GCTools. That means that if you have a French page/section and an English page/section that are asking for people to provide comments or feedback, they will never be the mirror of one another. And that is acceptable. There is no obligation to have the “work-in-progress” translated. The end product should however be made available in both official languages.
Be aware as well that not all public servants have the same official languages obligations. For example, some organizations are unilingual depending on the region they are based out of. In these circumstances, all the content they might post to the GCTools would be in one language only. Again, the same rules that apply offline also apply online.