[tunesmith]

Writing a lambda like that would require documentation. I wish Excel had a mode to look kinda like Jupyter except reactive (or observablehq except a desktop app), so I could easily add documentation for any cell and fold/unfold as I wish.

[zamadatix]

If you save it as a named function you can add a comment and that will appear as the tooltip while you're working on calling the function. If you're just wanting to comment how/why the function works in the cell you're defining or instantiating and immediately using it Excel has comments and notes you can attach to the cell or a group of cells.