How do I tell the VSCode Langauge server to use my Project.toml?

I have a project that I’m trying to edit in VSCode:

eric@tara ~/s/c/sql_explore (dev)> tree
├── Manifest.toml
├── Project.toml
├── main.jl
├── src
│   └── sql_explore.jl
└── test
    └── runtests.jl

The VSCode language server plugin seems to be working in my buffer, but it doesn’t understand any of the dependencies I’m adding to my project. The VSCode plugin docs don’t tell me how to configure a language server for a given project directory. What is the right way to do this?