Peter Geijerstam focused on enhancing the reliability of the modelcontextprotocol/rust-sdk by addressing a critical issue in MCP client tool discovery. He implemented a deterministic ordering mechanism for the ToolRouter and PromptRouter, ensuring that the list_all() output is consistently sorted by tool and prompt names. This fix, developed in Rust with a backend development focus, resolved intermittent failures caused by non-deterministic HashMap iteration, thereby improving integration stability and reproducibility across client calls and restarts. Although the work spanned one month and involved no new features, Peter’s targeted bug fix demonstrated depth in diagnosing and resolving subtle backend consistency issues.