The risk appears at the counter
A spreadsheet can warn that calibration is approaching, but the decisive control happens when a mechanic attempts to issue the tool.
If the tool is calibration controlled and the valid-use window is expired, the workflow must stop. This should not be a reminder, a color, or a manager preference.
Calibration data needs provenance
A tool record should show the calibration due date, certificate evidence, last calibration event, next action, and who validated the data.
Imports can accelerate setup, but they must not silently overwrite manually validated calibration fields. Audit confidence depends on knowing how the value got there.
Readiness is a future question
A calibrated tool that expires during a scheduled maintenance window can be operationally unavailable even if it is valid today.
Readiness views should show whether enough equivalent valid tools will exist for upcoming work, not just whether a single item is green in the moment.