What
When Claude Code builds an internal tool descriptor from an MCP server's tool info (MCP is the Model Context Protocol, used to connect external tools), it now carries over all of the original fields before setting name, underlyingV1ToolName, and the other explicitly listed properties, instead of dropping any fields that weren't explicitly named.
Why
This prevents information attached to an MCP tool from being silently discarded when Claude Code wraps it internally, which matters if other code later expects those extra fields to be present.