Withhold template-creation exception text from the client

Mirror the read_resource read-path: log the full traceback but raise a
ResourceError naming only the URI, so the original exception is not
leaked to the client. Reflow the ResourceNotFoundError docstring to 120.

Author: Kludex

src/mcp/server/mcpserver/exceptions.py

@@ -16,9 +16,8 @@ class ResourceError(MCPServerError):
 class ResourceNotFoundError(ResourceError):
     """Resource does not exist.
 
-    Raise this from a resource template handler to signal that the requested
-    instance does not exist; clients receive `-32602` (invalid params) per
-    SEP-2164.
+    Raise this from a resource template handler to signal that the requested instance does not exist;
+    clients receive `-32602` (invalid params) per SEP-2164.
     """
 
 

src/mcp/server/mcpserver/resources/templates.py

@@ -135,6 +135,7 @@ async def create_resource(
             )
         except ResourceError:
             raise
-        except Exception as e:
-            logger.exception("Error creating resource from template")
-            raise ResourceError(f"Error creating resource from template: {e}") from e
+        except Exception as exc:
+            logger.exception(f"Error creating resource from template {uri}")
+            # If an exception happens when creating the resource, we should not leak the exception to the client.
+            raise ResourceError(f"Error creating resource from template {uri}") from exc