Answer
It controls what populates the 'Object Description' field for that connection. If Method Name is set to a non-retrieval method (like a Create-type method rather than a GET-style method), the Object Description field will simply display empty, since that kind of method doesn't return descriptive data to show. Setting Method Name to an actual GET-type method instead causes Object Description to populate with meaningful, human-readable information about the connected object. Using a non-GET method doesn't cause an error — it just results in an empty Object Description, which is why changing the field can appear to 'do nothing' at first glance.