improve MCP error logging and fix duplicate auth call

Author: ricardosrib

src/sap_cloud_sdk/agentgateway/_customer.py

@@ -23,13 +23,14 @@
 import httpx
 from mcp import ClientSession
 from mcp.client.streamable_http import streamable_http_client
+from mcp.shared.exceptions import McpError
 
 from sap_cloud_sdk.agentgateway._dependencies_resolver import (
     EnvironmentDependenciesResolver,
     IntegrationDependenciesResolver,
 )
 from sap_cloud_sdk.agentgateway._models import (
-    AGWJsonRpcError,
+    JsonRpcError,
     CustomerCredentials,
     IntegrationDependency,
     MCPTool,
@@ -685,7 +686,7 @@ def _log_mcp_server_error(ord_id: str, exc: BaseException) -> None:
             body = exc.response.text
         except httpx.ResponseNotRead:
             body = None
-        rpc_error = AGWJsonRpcError.parse(body) if body else None
+        rpc_error = JsonRpcError.parse(body) if body else None
         if rpc_error:
             logger.error(
                 "Failed to load tools from %s — %s returned HTTP %d [JSON-RPC %d]: %s",
@@ -703,8 +704,21 @@ def _log_mcp_server_error(ord_id: str, exc: BaseException) -> None:
                 exc.response.status_code,
                 body[:500] if body else "(response body not available)",
             )
+    elif isinstance(exc, McpError):
+        logger.error(
+            "Failed to load tools from %s — JSON-RPC %d: %s",
+            ord_id,
+            exc.error.code,
+            exc.error.message,
+        )
     else:
-        logger.error("Failed to load tools from %s — skipping", ord_id, exc_info=exc)
+        logger.error(
+            "Failed to load tools from %s — %s: %s",
+            ord_id,
+            type(exc).__name__,
+            exc,
+            exc_info=exc,
+        )
 
 
 async def get_mcp_tools_customer(

src/sap_cloud_sdk/agentgateway/_lob.py

@@ -13,6 +13,7 @@
 import httpx
 from mcp import ClientSession
 from mcp.client.streamable_http import streamable_http_client
+from mcp.shared.exceptions import McpError
 from sap_cloud_sdk.destination import (
     create_client as create_destination_client,
     ConsumptionLevel,
@@ -29,7 +30,7 @@
     list_a2a_fragments,
 )
 from sap_cloud_sdk.agentgateway._models import (
-    AGWJsonRpcError,
+    JsonRpcError,
     Agent,
     AgentCard,
     AgentCardFilter,
@@ -307,7 +308,7 @@ def _log_mcp_server_error(fragment_name: str, exc: BaseException) -> None:
             body = exc.response.text
         except httpx.ResponseNotRead:
             body = None
-        rpc_error = AGWJsonRpcError.parse(body) if body else None
+        rpc_error = JsonRpcError.parse(body) if body else None
         if rpc_error:
             logger.error(
                 "Failed to load tools from fragment '%s' — %s returned HTTP %d [JSON-RPC %d]: %s",
@@ -325,10 +326,19 @@ def _log_mcp_server_error(fragment_name: str, exc: BaseException) -> None:
                 exc.response.status_code,
                 body[:500] if body else "(response body not available)",
             )
+    elif isinstance(exc, McpError):
+        logger.error(
+            "Failed to load tools from fragment '%s' — JSON-RPC %d: %s",
+            fragment_name,
+            exc.error.code,
+            exc.error.message,
+        )
     else:
         logger.error(
-            "Failed to load tools from fragment '%s' — skipping",
+            "Failed to load tools from fragment '%s' — %s: %s",
             fragment_name,
+            type(exc).__name__,
+            exc,
             exc_info=exc,
         )
 

src/sap_cloud_sdk/agentgateway/_models.py

@@ -98,24 +98,24 @@ class CustomerCredentials:
 
 
 @dataclass
-class AGWJsonRpcError:
+class JsonRpcError:
     """Parsed JSON-RPC error from an Agent Gateway response.
 
     AGW returns HTTP 200 with a JSON-RPC error body when the request is
-    structurally valid but the server encountered an error, e.g.:
-
-        {"jsonrpc": "2.0", "error": {"code": -32603, "message": "Internal Server Error"}}
+    structurally valid but the server encountered an error.
+    
+    Example: {"jsonrpc": "2.0", "error": {"code": -32603, "message": "Internal Server Error"}}
 
     Attributes:
-        code: JSON-RPC error code (e.g. -32603 for internal error).
+        code: JSON-RPC error code.
         message: Human-readable error message from AGW.
     """
 
     code: int
     message: str
 
     @classmethod
-    def parse(cls, text: str) -> "AGWJsonRpcError | None":
+    def parse(cls, text: str) -> "JsonRpcError | None":
         try:
             data = json.loads(text)
             error = data.get("error", {})

src/sap_cloud_sdk/agentgateway/agw_client.py

@@ -281,10 +281,12 @@ async def get_user_auth(
                     self._config.timeout,
                     self._token_cache,
                 )
-                return AuthResult(
+                result = AuthResult(
                     access_token=token,
                     gateway_url=credentials.gateway_url,
                 )
+                logger.info("User auth token obtained — gateway: '%s'", result.gateway_url)
+                return result
 
             # Check for transparent mode
             if detect_transparent_credentials():
@@ -299,10 +301,12 @@ async def get_user_auth(
                     self._config.timeout,
                     self._token_cache,
                 )
-                return AuthResult(
+                result = AuthResult(
                     access_token=token,
                     gateway_url=credentials.gateway_url,
                 )
+                logger.info("User auth token obtained — gateway: '%s'", result.gateway_url)
+                return result
 
             tenant = self._resolve_tenant_subdomain()
             token, gateway_url = await fetch_user_auth(
@@ -311,7 +315,9 @@ async def get_user_auth(
                 token_cache=self._token_cache,
                 gateway_url_cache=self._gateway_url_cache,
             )
-            return AuthResult(access_token=token, gateway_url=gateway_url)
+            result = AuthResult(access_token=token, gateway_url=gateway_url)
+            logger.info("User auth token obtained — gateway: '%s'", result.gateway_url)
+            return result
 
         except AgentGatewaySDKError:
             raise
@@ -437,10 +443,6 @@ async def list_mcp_tools(
 
             # LoB flow - requires tenant_subdomain
             tenant = self._resolve_tenant_subdomain()
-            if user_token:
-                auth = await self.get_user_auth(user_token)
-            else:
-                auth = await self.get_system_auth()
             return await get_mcp_tools_lob(
                 tenant,
                 auth.access_token,
@@ -590,7 +592,10 @@ async def call_mcp_tool(
                     tool, auth.access_token, self._config.timeout, **kwargs
                 )
 
-            auth = await self.get_user_auth(user_token)
+            if not user_token:
+                raise AgentGatewaySDKError(
+                    "user_token is required for LoB tool invocation."
+                )
             return await call_mcp_tool_lob(
                 tool, auth.access_token, self._config.timeout, **kwargs
             )

tests/agentgateway/unit/test_agw_client.py

@@ -563,7 +563,7 @@ async def test_lob_flow_with_user_token_uses_user_auth(self):
 
             await agw_client.list_mcp_tools(user_token="user-jwt")
 
-            assert mock_user_auth.call_count == 2
+            assert mock_user_auth.call_count == 1
             mock_lob.assert_called_once_with(
                 "my-tenant", "user-token-xyz", 60.0, filter=None
             )