Roblox Luau Language Server
Make sure you don't have both Lua by sumneko and Roblox LSP enabled.
Install In VSCode
Soon hookmetamethod and getconnections will have a better autocomplete
You can download the extension with precompiled binaries here: https://github.com/sponguss/KrnlLSP/releases
If you need to build your own binaries, follow the instructions at https://github.com/sumneko/lua-language-server