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Validates a proposed rule and reports its blast radius without creating a rule or modifying any mail: whether the rule is valid, warnings, how many existing messages and conversations currently match, and a plain-language summary of what would happen. Use it before create_mail_rule so the user can confirm — required practice before any large backfill.

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Parameters

Takes the same rule spec as create_mail_rule: optional name, match (all/any), conditions, actions, and an optional existingMail policy whose scope (inbox default, or all) decides where matches are counted.

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Example

Call
Result

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Notes

  • An invalid rule is reported in the result text (Rule is INVALID: …), not as a tool error — the question being asked is “would this work?”.
  • Counts above the 1000-message query window are reported as 1000+ (a lower bound).
  • Warnings cover actions a backfill would skip (forward, stopProcessing) and the heuristic nature of hasAttachment matching.