Add descriptions for schema-defined functions

languageservice/src/context-providers/descriptions.ts

@@ -1,6 +1,7 @@
 import descriptions from "./descriptions.json" assert {type: "json"};
 
 export const RootContext = "root";
+const FunctionContext = "functions";
 
 /**
  * Get a description for a built-in context
@@ -13,3 +14,12 @@ export function getDescription(context: string, key: string): string | undefined
   // eslint-disable-next-line @typescript-eslint/no-unsafe-return, @typescript-eslint/no-unsafe-member-access, @typescript-eslint/no-explicit-any
   return (descriptions as any)[context]?.[key]?.description;
 }
+
+/**
+ * Get a description for a context function
+ * This will not include functions defined by the expressions library (e.g. `contains`, `fromJSON`, etc.)
+ * @param name Name of the function, for example `hashFiles`
+ */
+export function getFunctionDescription(name: string): string | undefined {
+  return getDescription(FunctionContext, name);
+}