Large language models often struggle with 'citation hallucination,' fabricating academic references or misattributing details. The DOI Citation Verifier acts as a Model Context Protocol (MCP) server that mandates verification for every academic citation an LLM attempts to generate. By querying CrossRef's extensive database in real-time, it validates citation details, ensuring that only confidently matched, real publications with valid DOIs are cited, thereby eliminating the problem of non-existent or incorrect references.