Checking the material management API in Panda3D, I discovered that Panda3D BAM Exporter does not store the names of materials. The only way to access the description is to use indexes.
mats = self.model.findAllMaterials()
mats1 = mats.getMaterial(0)
Perhaps this is due to the BAM version, so a quick check showed that the egg2bam.exe utility saves the names of the materials.