MCP Server Response Result Consistency Optimization

Issue: MCP Server Tool Result Serialization Uses Wrong ObjectMapper

Expected Behavior

MCP server tool results should use the Spring-configured ObjectMapper for serialization.

Current Behavior

MCP server tool result serialization uses the static OBJECT_MAPPER from org.springaicommunity.mcp.method.tool.utils.JsonParser instead of the configured mcpServerObjectMapper. This causes tool responses to contain null fields instead of excluding them as configured.

Context

I am using Spring AI MCP Server with SSE transport. I have configured a custom ObjectMapper bean with NON_NULL inclusion, but tool results still contain null fields.

The issue appears to be in the serialization path when converting tool method return values to CallToolResult content. The JsonParser utility class uses its own static ObjectMapper that doesn't respect my Spring configuration.

I need clean JSON responses without null fields for client consumption. Current workarounds involve manual null filtering in each tool method, which is not maintainable.

The requested fix is to either make the tool result serialization use the configured mcpServerObjectMapper, or ensure org.springaicommunity.mcp.method.tool.utils.JsonParser OBJECT_MAPPER configuration matches the server configuration.

Start with org.springaicommunity.mcp.method.tool.utils.JsonParser and trace the serialization path that converts tool return values into CallToolResult content. Compare its static OBJECT_MAPPER with the configured mcpServerObjectMapper; done means tool results honor the server's NON_NULL configuration without requiring manual filtering in each tool method.