A method for parsing and verifying the contents of a command script containing a token and written in a scripting language. A first, relatively rapidly accessible data store and a second, less rapidly accessible data store are provided. Each data store contains function signature definitions which include a function name and an associated parameter list of zero or more parameter specifications. The first data store contains function names associated with commands that do not require data retrieval for completion. The second data store contains function names associated with commands that, unlike those in the first data store, do require data retrieval for completion. A potential function name and its associated arguments, if any, are recognized within the token. The first data store is searched for a matching function signature, having a function name matching the potential function name, and a parameter list matching the parsed potential function arguments. If no match is found, the second data store is then searched in a similar manner for a matching function signature.