TLA+ Toolbox is an IDE based on Eclipse, and for a long time it has been the official environment to work with TLA+ tools. See: https://lamport.azurewebsites.net/tla/toolbox.html
Since around 2020 the development focus has moved to improve the VScode plugin experience. The TLA+ Toolbox has now moved to archived mode. The current bugs won't be fixed and as as dependency rots, eventually it will stop being distributed as well. Therefore it is not recommended for daily use.
If you haven't yet, you should consider moving to the VSCode official extension:
Feel free to update this page with missing or useful information as you see fit. These are some ideas if you'd like to contribute:
We value feedback a lot. * If you have suggestions on how to improve this structure of this guide, please use: https://github.com/tlaplus/vscode-tlaplus/issues/423#issuecomment-3391933491 * If you have suggestions on how to improve the extension, create a new issue on https://github.com/tlaplus/vscode-tlaplus