diff --git a/autogpt_platform/backend/backend/api/features/chat/tools/run_block.py b/autogpt_platform/backend/backend/api/features/chat/tools/run_block.py
index c4e6e5ffc4..a8df8d0c6d 100644
--- a/autogpt_platform/backend/backend/api/features/chat/tools/run_block.py
+++ b/autogpt_platform/backend/backend/api/features/chat/tools/run_block.py
@@ -106,6 +106,9 @@ class RunBlockTool(BaseTool):
                     and discriminator_value in field_info.discriminator_mapping
                 ):
                     effective_field_info = field_info.discriminate(discriminator_value)
+                    # For host-scoped credentials, add the discriminator value
+                    # (e.g., URL) so _credential_is_for_host can match it
+                    effective_field_info.discriminator_values.add(discriminator_value)
                     logger.debug(
                         f"Discriminated provider for {field_name}: "
                         f"{discriminator_value} -> {effective_field_info.provider}"
diff --git a/autogpt_platform/backend/backend/api/features/chat/tools/utils.py b/autogpt_platform/backend/backend/api/features/chat/tools/utils.py
index c48cd09458..80a842bf36 100644
--- a/autogpt_platform/backend/backend/api/features/chat/tools/utils.py
+++ b/autogpt_platform/backend/backend/api/features/chat/tools/utils.py
@@ -295,7 +295,9 @@ def find_matching_credential(
             continue
         if cred.type not in field_info.supported_types:
             continue
-        if cred.type == "oauth2" and not _credential_has_required_scopes(cred, field_info):
+        if cred.type == "oauth2" and not _credential_has_required_scopes(
+            cred, field_info
+        ):
             continue
         if cred.type == "host_scoped" and not _credential_is_for_host(cred, field_info):
             continue