fix

Author: timothedelion

packages/gg_api_core/src/gg_api_core/mcp_server.py

@@ -225,30 +225,44 @@ async def _parameter_preprocessing_middleware(self, context: MiddlewareContext,
         params = context.params
         arguments = params.get("arguments", {})
 
+        # Log what we received for debugging
+        logger.debug(f"Middleware received arguments: {arguments} (type: {type(arguments)})")
+
         # If arguments is empty or not a dict, nothing to preprocess
         if not isinstance(arguments, dict):
+            logger.debug(f"Arguments is not a dict, skipping preprocessing")
             return await call_next(context)
 
         # Look for stringified JSON in parameter values
         preprocessed_arguments = {}
+        modified = False
+
         for key, value in arguments.items():
+            logger.debug(f"Processing parameter '{key}': {repr(value)} (type: {type(value)})")
             if isinstance(value, str) and value.strip().startswith("{"):
                 # Looks like stringified JSON, try to parse it
                 try:
                     parsed = json.loads(value)
                     if isinstance(parsed, dict):
-                        logger.debug(f"Preprocessing parameter '{key}': converted JSON string to dict")
+                        logger.info(f"Preprocessed parameter '{key}': converted JSON string to dict")
                         preprocessed_arguments[key] = parsed
+                        modified = True
                     else:
                         preprocessed_arguments[key] = value
-                except (json.JSONDecodeError, ValueError):
+                except (json.JSONDecodeError, ValueError) as e:
                     # Not valid JSON, keep original value
+                    logger.debug(f"Failed to parse '{key}' as JSON: {e}")
                     preprocessed_arguments[key] = value
             else:
                 preprocessed_arguments[key] = value
 
-        # Update context with preprocessed arguments
-        context.params["arguments"] = preprocessed_arguments
+        # Update context with preprocessed arguments if we modified anything
+        if modified:
+            context.params["arguments"] = preprocessed_arguments
+            # Also update context.message.arguments which FastMCP uses
+            if hasattr(context, "message") and hasattr(context.message, "arguments"):
+                context.message.arguments = preprocessed_arguments
+            logger.debug(f"Updated arguments: {preprocessed_arguments}")
 
         return await call_next(context)
 

tests/test_middleware_preprocessing.py

@@ -52,16 +52,29 @@ def test_middleware_converts_stringified_json_params(self):
 
         mcp = GitGuardianPATEnvMCP("test", personal_access_token="test_token")
 
-        # Create a mock context with stringified JSON parameters
+        # Create a mock context with stringified JSON parameters that mirrors FastMCP structure
+        class MockMessage:
+            def __init__(self):
+                self.name = "list_repo_occurrences"
+                self.arguments = {"params": '{"source_id": 9036019, "get_all": true}'}
+
         class MockContext:
             method = "tools/call"
-            params = {"arguments": {"params": '{"source_id": 9036019, "get_all": true}'}}
+
+            def __init__(self):
+                self.message = MockMessage()
+                self.params = {"arguments": {"params": '{"source_id": 9036019, "get_all": true}'}}
 
         async def mock_call_next(ctx):
-            # Verify the params were preprocessed
+            # Verify both context.params and context.message.arguments were preprocessed
             assert isinstance(ctx.params["arguments"]["params"], dict)
             assert ctx.params["arguments"]["params"]["source_id"] == 9036019
             assert ctx.params["arguments"]["params"]["get_all"] is True
+
+            # FastMCP uses context.message.arguments, so verify that's updated too
+            assert isinstance(ctx.message.arguments["params"], dict)
+            assert ctx.message.arguments["params"]["source_id"] == 9036019
+            assert ctx.message.arguments["params"]["get_all"] is True
             return "success"
 
         context = MockContext()