The handoff is part of the product.
A document can arrive while responsibility remains unclear. The next person inherits the choices it explains and the questions it leaves behind.
Imagine a contractor receiving a drawing that specifies a material without explaining why it was chosen. When that material becomes unavailable, an alternative looks equivalent on the dimensions the drawing records. The original choice may have depended on a condition the drawing leaves out. The contractor can follow the document and still miss the intention.
The same problem appears in software. A designer expects a response to arrive immediately. An engineer has to allow for a delay. Support inherits questions about a limit without knowing which risk it was meant to prevent. Each person can complete an assigned task while the service becomes less understandable at the points between them.
The status of a decision
What goes missing is often the status of a decision. Was this detail essential, provisional, or an accident of the first version? A specification that treats them all alike asks the next person to guess where they can exercise judgment.
Documenting everything is an expensive way to avoid that choice. A long record may contain the explanation someone needs while making it difficult to find. A useful handoff preserves the context that could change the next decision: what was chosen, why, what remains uncertain and who can revisit it.
For the contractor, useful context might identify the condition a substitute has to satisfy and the person able to assess it. For an engineer, it might explain what the customer must understand while a response is delayed. A support colleague might need the reason for a limit and the alternatives they are authorized to offer. The right detail depends on the next decision someone has to make.
What the next person can do
A handoff is worth testing from the receiving side. Ask the next person to explain the decision they may have to make, which parts are fixed and where they will go if an assumption fails. A gap in that explanation can expose missing context while the people who have it are still available. Agreement that a document was received cannot do the same work.
Documents are not the only possible gap. A named owner may lack the authority, time, or access to resolve the problem. If that becomes clear, the handoff needs a change in responsibility or resources. More instructions would make the shortage better described without fixing it.
New information also needs a route back. The contractor may discover that the specified material is unavailable or that a substitute raises a question the drawing never addressed. Seen this way, a handoff leaves a relationship between the people making successive decisions. We find that more useful to think about than a moment when one person's part is declared complete.