`declaresAnyFields` decides whether a tool is auto-invoked with `{}` or asked
about, and it counts a required name a schema never declares — so the #2224
check making such a union render nothing must not be read as "no arguments".
Nothing changed here; the invariant just had no test of its own.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PxYT4eKdnx1yRw7x4bW7Ts
Signed-off-by: cliffhall <cliff@futurescale.com>