A search function can be technically accessible and still malfunction for visitors. That is why good monitoring combines technical signals with search quality, product clicks, current catalog data and conversion measurement.
Start with the search experience itself. Track how many searches yield useful results, how often visitors click through, and where zero-result searches or error messages increase., split this data out where possible by store, device, search type, and key category, so that a local problem does not disappear into a general average.
Measure not only the average response time, but also slow outliers. Especially the slowest five or one percent of the requests can cause a lot of frustration. Combine response time with error rates and check autocomplete, search results, filters, and product enrichment separately.
Check that new products, stock changes and prices appear in the search index within the agreed time. Note growing queues, failed updates and differences between source catalog and index. After all, an available search function with outdated information can still raise wrong expectations.
Monitor search events, product clicks, and orders as separate chains. A sudden conversion drop can occur from missing tracking while search is working normally. Link warnings to an owner, level of severity and clear first check, so that a signal actually leads to action.
Discuss which measurements, responsibilities and restoration routes fit your online stores and technical environment.