Return table_comment and column_comment as part of list_table, describe_table tool calls

Example -
```
interface TableMetadata {
  table_name: string;
  table_comment: string;
}
```

...

```
 case "list_tables": {
      const results = await executeQuery<TableMetadata[]>(
        "SELECT table_name, table_comment FROM information_schema.tables WHERE table_schema = DATABASE()"
      );
...
```