The James Webb Space Telescope has no cameras mounted that look at itself. If a malfunction occurred on-board, would any other telescope be able to resolve it with sufficient clarity to provide useful images (assuming that any problem involved one of its large components such as the sun shield or mirror array)?
The Virtual Telescope Project has provided a photo of the James Webb Telescope taken from a ground-based telescope. Whether you consider a single bright dot to be 'useful' (in any scientific sense) remains to be seen, but I would guess that this at least allows the observers to confirm that it's where it's supposed to be, rather than in another location and giving off misleading telemetry.
source: AliveUniverse.today James Webb in L2 ripreso dal Virtual Telescope Project
The James Webb Space Telescope has no cameras mounted that look at itself.
But there is a camera! It took this selfie of the objective mirrors:
A selfie taken by a camera onboard the James Webb Space Telescope (NASA)