Worked on enhancing MCP fingerprinting reliability within the google/tsunami-security-scanner-plugins repository, focusing on backend development using Java and unit testing. Addressed a bug that previously caused false positives by refining the WebServiceFingerprinter logic, introducing the Accept header for MCP requests, and ensuring that 406 Not Acceptable responses no longer triggered incorrect detections. Developed and integrated regression tests to validate behavior with JSON-RPC error bodies, supporting long-term stability and accuracy. The work included thorough documentation and tracked changes, resulting in more robust detection of MCP servers across diverse configurations and reducing the likelihood of future regressions in the fingerprinting process.