Commands can be parsed, in a very limited way.

src/main/java/net/minecraft/commands/tree/LiteralCommandNode.java

@@ -1,5 +1,7 @@
 package net.minecraft.commands.tree;
 
+import net.minecraft.commands.exceptions.IllegalCommandArgumentException;
+
 public class LiteralCommandNode extends CommandNode {
     private final String literal;
     private final Runnable executor;
@@ -16,4 +18,11 @@ public class LiteralCommandNode extends CommandNode {
     public Runnable getExecutor() {
         return executor;
     }
+
+    @Override
+    public void parse(String command) throws IllegalCommandArgumentException {
+        if (!command.equals(literal)) {
+            throw new IllegalCommandArgumentException();
+        }
+    }
 }