diff --git a/docs/querying/api.md b/docs/querying/api.md
index b767f04b8a..1fee171eb1 100644
--- a/docs/querying/api.md
+++ b/docs/querying/api.md
@@ -208,6 +208,10 @@ $ curl 'http://localhost:9090/api/v1/query_range?query=up&start=2015-07-01T20:10
 
 ## Querying metadata
 
+Prometheus offers a set of API endpoints to query metadata about series and their labels.
+
+NOTE: These API endpoints may return metadata for series for which there is no sample within the selected time range, and/or for series whose samples have been marked as deleted via the deletion API endpoint. The exact extent of additionally returned series metadata is an implementation detail that may change in the future.
+
 ### Finding series by label matchers
 
 The following endpoint returns the list of time series that match a certain label set.
@@ -854,7 +858,7 @@ $ curl http://localhost:9090/api/v1/status/runtimeinfo
 }
 ```
 
-**NOTE**: The exact returned runtime properties may change without notice between Prometheus versions.
+NOTE: The exact returned runtime properties may change without notice between Prometheus versions.
 
 *New in v2.14*
 
@@ -883,7 +887,7 @@ $ curl http://localhost:9090/api/v1/status/buildinfo
 }
 ```
 
-**NOTE**: The exact returned build properties may change without notice between Prometheus versions.
+NOTE: The exact returned build properties may change without notice between Prometheus versions.
 
 *New in v2.14*
 
@@ -1014,6 +1018,9 @@ Example:
 $ curl -X POST \
   -g 'http://localhost:9090/api/v1/admin/tsdb/delete_series?match[]=up&match[]=process_start_time_seconds{job="prometheus"}'
 ```
+
+NOTE: This endpoint marks samples from series as deleted, but will not necessarily prevent associated series metadata from still being returned in metadata queries for the affected time range (even after cleaning tombstones). The exact extent of metadata deletion is an implementation detail that may change in the future.
+
 *New in v2.1 and supports PUT from v2.9*
 
 ### Clean Tombstones