diff --git a/tests/perf/query_cases/paper_ffx_balanced/case.toml b/tests/perf/query_cases/paper_ffx_balanced/case.toml
index b90af2e0220..c014e7870be 100644
--- a/tests/perf/query_cases/paper_ffx_balanced/case.toml
+++ b/tests/perf/query_cases/paper_ffx_balanced/case.toml
@@ -187,7 +187,7 @@ query = "WITH ff AS (SELECT host, SUM(metric_value) AS fm, COUNT(metric_value) A
 warmup = 0
 iterations = 1
 
-# Diagnostic single executions are excluded from benchmark comparison.
+# Diagnostic queries are run once by the runner and must be excluded from performance analysis.
 [[scenario.queries]]
 name = "diagnostic_explain_raw_wide"
 kind = "sql"
diff --git a/tests/perf/query_cases/paper_ffx_hot/case.toml b/tests/perf/query_cases/paper_ffx_hot/case.toml
index e6294f8e603..258864b786b 100644
--- a/tests/perf/query_cases/paper_ffx_hot/case.toml
+++ b/tests/perf/query_cases/paper_ffx_hot/case.toml
@@ -119,7 +119,7 @@ query = "WITH ff AS (SELECT host, SUM(metric_value) AS fm, COUNT(metric_value) A
 warmup = 0
 iterations = 1
 
-# Diagnostic single executions are excluded from benchmark comparison.
+# Diagnostic queries are run once by the runner and must be excluded from performance analysis.
 [[scenario.queries]]
 name = "diagnostic_explain_raw_wide"
 kind = "sql"
diff --git a/tests/perf/query_cases/paper_ffx_low/case.toml b/tests/perf/query_cases/paper_ffx_low/case.toml
index 042f579e807..a8c6b57772b 100644
--- a/tests/perf/query_cases/paper_ffx_low/case.toml
+++ b/tests/perf/query_cases/paper_ffx_low/case.toml
@@ -119,7 +119,7 @@ query = "WITH ff AS (SELECT host, SUM(metric_value) AS fm, COUNT(metric_value) A
 warmup = 0
 iterations = 1
 
-# Diagnostic single executions are excluded from benchmark comparison.
+# Diagnostic queries are run once by the runner and must be excluded from performance analysis.
 [[scenario.queries]]
 name = "diagnostic_explain_raw_wide"
 kind = "sql"