Our primary findings demonstrate that the structures generated from the execution of APIs more often match the original structure, and appending CIF files to output increases errors; see Figure . API execution effectively increases the number of generated structures matching the original structure: a true match occurs in 36% for "API, code" and 30% for "API, code+CIF", while only 8% for "CIF parser, code+CIF". Including CIF increases LLM hallucinations: our parsers failed to generate a valid structure in only 5% of cases for "API, code", but in 14% for "API, code+CIF". Hallucinations -where the generated output code or CIF cannot be translated into a valid crystal representation -often result from the error "supplied space group is incompatible with the supplied lattice parameters".