Developed and delivered the Deferred Tool Loading feature for the bytedance/deer-flow repository, targeting improved tool selection accuracy and reduced context bloat in environments with multiple MCP servers. The solution introduced a tool_search configuration, a deferred tool registry, and middleware to filter deferred tools from model binding, all implemented in Python. Comprehensive unit testing ensured reliability and maintainability of the new functionality. This work enhanced backend development practices and API design, laying the groundwork for scalable tool loading and improved developer ergonomics. The approach focused on modular middleware integration and robust test coverage, contributing to system reliability and future extensibility.