If I understood your question correctly, it seems that tasks are not very well defined which is root cause of this issue. While user stories are good to describe a task, one should try to include different mediums to translate and define business need in accurate form for related team members. Project team members has different view points based on their Role in the project, hence including different supporting documents for a feature becomes vital for easy preview and Sign-Off. Once a well groomed Backlog if ready it becomes easier to define the workflow in tangible easy steps.
For e.g. UI, Wireframes, Workflow diagrams, Sequence diagrams, Screenflow depicting different screens and complete dataflow, API signatures, brief objective, Ambiguity check with other business case, test data (username/password/json/xml structure of data etc. etc.), supported environments, etc.
Task/Feature Definition, Backlog Grooming: You must review all relevant data points applicable to your product and ensure that these inputs are well reviewed and discussed to be finalized for any user story to be termed as "Ready for Development". Call the relevant filtered inputs for development as "Check List for User story" creation. Using this check list define clear and non-ambiguous requirement for development, ensure every user story has these inputs as mandatory parameters. Keep your backlog well groomed and Product repository easy accessible and updated for every team member's access and review.
Task Handover from Development Team to QA: Work with Developers to define the Inputs which they are supposed to provide when task is moved to "Ready to Test" Status. Development team must run unit test cases and review implementation low level design validation. A checklist must be submitted as proof for handover to quality team. Release Notes to QA, Deployment Guide, Unit testcase execution report, test data username/password feature-data used (for example URL, username/password, book name if project is about online bookshelf), Impact area etc..
Task Validation by QA: QA team members must be able to create testcases based on User stories as defined by you. These test-cases will form a part acceptance criteria as well. So review the testcases along with development team, get most important and frequent testcases included in unit test cases for development team's perusal.
QA team will provide Test execution report based and log all test execution in details. like URL/App version, Username, Password, Feature Name which is reviewed, API captures, Session Captures, screenshots, steps to replicate, actual vs expected output, environment details in which this issue is replicating (all/specific environment) etc.
QA Handover to Deployment: Verified tasks can be taken forward for production deployment. This can be supported using deployment guidelines, where agreed way for deployment of verified tasks, with version control and rollout plans are well defined with Final User acceptance validation for Defined Business Requirements.
Success Criteria This must be included at Project level for definition of Project/Milestone/Release success.
You can include/exclude the steps based on kind of work and requirement, but It is very important to define the framework or Workflow which is reviewed and agreed by every team member involved in the project.