Advice about boundaries often stops at the sentence: say what you need, be clear, hold firm. The sentence matters. It is not the whole mechanism.
A boundary operates inside a system of access, dependence, consequence and support. If those conditions make refusal unsafe or impossible, better wording cannot carry the full load.
Define the rule in terms of action
A wish describes the preferred outcome. A boundary describes what access is available and what action follows when the condition is not met. The difference is practical rather than aggressive.
Specificity helps: which channel, what subject, which time, what response. It reduces the opportunity for a disagreement about the rule to become a disagreement about whether the rule existed.
Check who pays for enforcement
A boundary that requires constant vigilance can become another job. If the person with least power must detect every breach, repeat the rule and absorb the reaction, the surrounding system is not supporting the boundary.
Useful structures distribute the work. They may limit access by default, record contact, route requests or involve somebody with the authority to act.
Design the consequence before the test
Consequences are easier to state than to carry out, particularly when they affect housing, work, care or belonging. Planning needs to include what is safe, proportionate and actually within the person's control.
This is not an argument for weaker boundaries. It is an argument for honest ones, supported by conditions that make follow-through possible.
Allow boundaries to change
A boundary can be revised when circumstances or knowledge changes. Revision does not prove that the earlier limit was insincere. It proves that rules operate in time.
The important distinction is between a chosen revision and erosion through pressure. A good system records the difference, even if the record is only a private sentence written down before the conversation.
If the person with least power must absorb every reaction, the system is not supporting the boundary.