# hooks-validate-buf-len Hook API [sto_validate](https://xrpl-hooks.readme.io/v2.0/reference/sto_validate) requires non-empty input buffer. This check warns about empty input in calls to `sto_validate` (if it's specified by a constant - variable parameter is ignored). [Read more](https://xrpl-hooks.readme.io/v2.0/docs/serialized-objects)