Crowbar tool has been a source modding MDL tool for a long time but recently has gotten GoldSrc MDL support and in its latest update (.49) has gained many improvements.
Decompiles have nicely formatted QC code as well as recognizing things like multiple $texrendermodes on textures. It has multiple GoldSrc games & mods configs ready to set up and is able to compile directly into the steam dir & models folder of your desired game.
https://steamcommunity.com/groups/CrowbarTool