Wall Worm is a script and tool developer focused on 3ds Max and various Max-related pipelines. Historically, Wall Worm was devoted soley to optimizing the Source Engine asset pipeline. The Wall Worm toolset itself is a Source-only toolset. However, many new tools are generic in nature (for any game engine, VFX, VIZ, etc), such as the CorVex plugin and most other new tools.
See the official Autodesk blog feature about Wall Worm developer Shawn Olson, Wall Worm and Black Mesa: From Black Sheep to Black Mesa and Beyond.
Wall Worm tools allow you to create assets for Source in a way that was not possible before. You can build models, textures and levels inside one environment (3ds Max) and compile them straight into Source. Wall Worm tools have been used in the pipelines of many games including Dear Esther, Black Mesa and by designers of CS:GO Operation maps and many more.
Wall Worm works in collaboration with other 3ds Max/Source developers to help enhance all the tools available to designers and mod teams.
$jigglebones are bones that can automatically generate secondary motion without being animated. Making a $jigglebone in WWMT requires you to use the hierarchy tab in the command panel, which may be a new area for less experienced modelers.
Making a ragdoll requires you to use the hierarchy tab in the command panel, which may be a new area for less experienced modelers. Watch the video here to get a basic overview of how to make a ragdoll for Source.
The Level of Detail Generator on the Level of Detail Tools Rollout lets you generate LOD models from the root mesh. The tool will make lower-res versions of your model so that less polygons are rendered in-game when players move farther away.