Worked on the modelcontextprotocol/go-sdk repository, focusing on backend development and API design using Go. Addressed a critical issue in JSON handling by ensuring the ReadOnlyHint field in ToolAnnotations is always serialized, regardless of its value. This change aligned the SDK’s behavior with OpenAI MCP specification requirements, reducing integration risks for downstream clients and supporting reliable MCP app submissions. The solution involved removing the omitempty directive from the JSON serialization logic, thereby preserving explicit hints in the wire format. The work demonstrated careful attention to external protocol compliance and data integrity, contributing to more robust and predictable API interactions.