Creates an error tool result.
Back-compat alias for toolStructuredError — maps to the
conservative internal / non-retryable envelope. New code should call
toolStructuredError directly with the correct category; this alias
exists so the ~64 legacy call sites keep working during the #2649
migration sweep.
The error message
A ToolResult with isError set to true and an internal envelope
MCP exports - MCP server implementation Split from index.ts for file size compliance (Issue #285) Updated Issue #538: Added missing tool registration exports