diff --git a/src/google/adk/plugins/bigquery_agent_analytics_plugin.py b/src/google/adk/plugins/bigquery_agent_analytics_plugin.py
index 7c67e0fa13..f00b8cfbf3 100644
--- a/src/google/adk/plugins/bigquery_agent_analytics_plugin.py
+++ b/src/google/adk/plugins/bigquery_agent_analytics_plugin.py
@@ -842,13 +842,20 @@ def _sanitize_free_text(
   closed; a quoted fragment is walked through the full blob sanitizer
   from the first quote. A stray
   escape in the prose gap could shift a consumer's parse boundaries and
-  also fails closed. Quote-free, container-free prose passes through.
+  also fails closed. Quote-free, container-free prose still gets the
+  plain-text credential-pattern pass: this function is the fallback for
+  every non-container-shaped string reaching the recursive sanitizer
+  (tool args/results, state deltas, usage metadata, A2A payloads,
+  schemas), so an unkeyed "Authorization: Bearer ..."-shaped value must
+  not pass through unredacted just because it never picked up a JSON
+  container token or quote.
   """
   if "{" in text or "[" in text:
     return "[UNPARSEABLE_JSON_BLOB]", True, True
   quote_idx = text.find('"')
   if quote_idx == -1:
-    return text, False, False
+    redacted, changed = _redact_sensitive_patterns(text)
+    return redacted, changed, changed
   gap = text[:quote_idx]
   if "\\" in gap:
     return "[UNPARSEABLE_JSON_BLOB]", True, True
@@ -856,9 +863,10 @@ def _sanitize_free_text(
   t_sanitized, changed, truncated = _sanitize_json_blob(
       tail, seen, depth + 1, max_len, budget
   )
-  if not changed:
+  gap_sanitized, gap_changed = _redact_sensitive_patterns(gap)
+  if not changed and not gap_changed:
     return text, False, False
-  return gap + t_sanitized, True, truncated
+  return gap_sanitized + t_sanitized, True, truncated
 
 
 def _sanitize_json_blob(
@@ -978,7 +986,16 @@ def _sanitize_json_blob(
     suffix_text = suffix if not s_changed else s_sanitized
     return prefix_text + suffix_text, True, p_truncated or s_truncated
   if not stripped.startswith(("{", "[")):
-    return value, False, False
+    # Plain prose is the common case for tool args/results, state deltas,
+    # usage metadata, A2A payloads, and schemas — none of which are
+    # container-shaped, so without this pass a value like
+    # "Authorization: Bearer sk-..." embedded under an unrecognized key
+    # (e.g. a tool's own error/status message) would reach BigQuery
+    # completely unredacted. This mirrors the pattern-based pass already
+    # applied to URI segments, Part-content text, and error/traceback
+    # text elsewhere in this file.
+    redacted, changed = _redact_sensitive_patterns(value)
+    return redacted, changed, changed
 
   # Enforce the inspection limit BEFORE materializing: json.loads runs
   # synchronously on the callback path and can allocate far beyond the
diff --git a/tests/unittests/plugins/test_bigquery_agent_analytics_plugin.py b/tests/unittests/plugins/test_bigquery_agent_analytics_plugin.py
index 9243d611d5..8067f183af 100644
--- a/tests/unittests/plugins/test_bigquery_agent_analytics_plugin.py
+++ b/tests/unittests/plugins/test_bigquery_agent_analytics_plugin.py
@@ -439,6 +439,53 @@ def test_recursive_smart_truncate_redaction():
   assert truncated["nested"]["normal"] == "value"
 
 
+def test_recursive_smart_truncate_redacts_credentials_in_free_text_values():
+  """A credential embedded in prose under an unrecognized key must still be
+  redacted, not just an exact-matching dict key.
+
+  Regression test: tool args/results, state deltas, usage metadata, A2A
+  payloads, and schemas all reach BigQuery through this function, and none
+  of them are container-shaped JSON strings in the common case, so a value
+  like an "Authorization: Bearer ..." token embedded in an ordinary status
+  or error message previously passed through completely unredacted.
+  """
+  obj = {
+      "status": "ok",
+      "message": "Authorization: Bearer sk-abcdef123456xyz",
+  }
+  truncated, is_truncated = (
+      bigquery_agent_analytics_plugin._recursive_smart_truncate(obj, -1)
+  )
+  assert is_truncated
+  assert "sk-abcdef123456xyz" not in truncated["message"]
+  assert truncated["message"] == "Authorization: [REDACTED]"
+
+  obj2 = {
+      "status": "ok",
+      "message": "here is the api_key: sk-abcdef123456xyz please use it",
+  }
+  truncated2, is_truncated2 = (
+      bigquery_agent_analytics_plugin._recursive_smart_truncate(obj2, -1)
+  )
+  assert is_truncated2
+  assert "sk-abcdef123456xyz" not in truncated2["message"]
+
+  # Benign prose must remain byte-identical.
+  obj3 = {"status": "ok", "message": "everything is fine, no secrets here"}
+  truncated3, is_truncated3 = (
+      bigquery_agent_analytics_plugin._recursive_smart_truncate(obj3, -1)
+  )
+  assert not is_truncated3
+  assert truncated3 == obj3
+
+  # A plain (non-dict-wrapped) string leaf must also be covered.
+  leaf, leaf_truncated = bigquery_agent_analytics_plugin._recursive_smart_truncate(
+      "Authorization: Bearer sk-abcdef123456xyz", -1
+  )
+  assert leaf_truncated
+  assert "sk-abcdef123456xyz" not in leaf
+
+
 class TestBigQueryAgentAnalyticsPlugin:
   """Tests for the BigQueryAgentAnalyticsPlugin."""