Add tests for MCPServer.read_resource exception handling

src/mcp/server/experimental/request_context.py

@@ -91,7 +91,7 @@ def validate_task_mode(
             error = ErrorData(code=METHOD_NOT_FOUND, message="This tool does not support task-augmented invocation")
 
         if error is not None and raise_error:
-            raise MCPError(code=error.code, message=error.message)
+            raise MCPError.from_error_data(error)
 
         return error
 

src/mcp/server/lowlevel/server.py

@@ -795,12 +795,7 @@ async def _handle_request(
 
             await message.respond(response)
         else:  # pragma: no cover
-            await message.respond(
-                types.ErrorData(
-                    code=types.METHOD_NOT_FOUND,
-                    message="Method not found",
-                )
-            )
+            await message.respond(types.ErrorData(code=types.METHOD_NOT_FOUND, message="Method not found"))
 
         logger.debug("Response sent")
 

src/mcp/server/mcpserver/server.py

@@ -348,15 +348,16 @@ async def read_resource(self, uri: AnyUrl | str) -> Iterable[ReadResourceContent
 
         context = self.get_context()
         resource = await self._resource_manager.get_resource(uri, context=context)
-        if not resource:  # pragma: no cover
+        if not resource:
             raise ResourceError(f"Unknown resource: {uri}")
 
         try:
             content = await resource.read()
             return [ReadResourceContents(content=content, mime_type=resource.mime_type, meta=resource.meta)]
-        except Exception as e:  # pragma: no cover
-            logger.exception(f"Error reading resource {uri}")
-            raise ResourceError(str(e))
+        except Exception as exc:
+            logger.exception(f"Error getting resource {uri}")
+            # If an exception happens when reading the resource, we should not leak the exception to the client.
+            raise ResourceError(f"Error reading resource {uri}") from exc
 
     def add_tool(
         self,