fix: set conditional capabilities upon MCP client session initialization (#26234)

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: Novice <novice12185727@gmail.com>

api/core/entities/mcp_provider.py

@@ -14,7 +14,6 @@ from core.helper.provider_cache import NoOpProviderCredentialCache
 from core.mcp.types import OAuthClientInformation, OAuthClientMetadata, OAuthTokens
 from core.tools.entities.common_entities import I18nObject
 from core.tools.entities.tool_entities import ToolProviderType
-from core.tools.utils.encryption import create_provider_encrypter
 
 if TYPE_CHECKING:
     from models.tools import MCPToolProvider
@@ -272,6 +271,8 @@ class MCPProviderEntity(BaseModel):
 
     def _decrypt_dict(self, data: dict[str, Any]) -> dict[str, Any]:
         """Generic method to decrypt dictionary fields"""
+        from core.tools.utils.encryption import create_provider_encrypter
+
         if not data:
             return {}
 

api/core/mcp/session/client_session.py

@@ -109,12 +109,16 @@ class ClientSession(
         self._message_handler = message_handler or _default_message_handler
 
     def initialize(self) -> types.InitializeResult:
-        sampling = types.SamplingCapability()
-        roots = types.RootsCapability(
-            # TODO: Should this be based on whether we
-            # _will_ send notifications, or only whether
-            # they're supported?
-            listChanged=True,
+        # Only set capabilities if non-default callbacks are provided
+        # This prevents servers from attempting callbacks when we don't actually support them
+        sampling = types.SamplingCapability() if self._sampling_callback is not _default_sampling_callback else None
+        roots = (
+            types.RootsCapability(
+                # Only enable listChanged if we have a custom callback
+                listChanged=True,
+            )
+            if self._list_roots_callback is not _default_list_roots_callback
+            else None
         )
 
         result = self.send_request(