A broken pot turned on its side can shelter a toad. It cannot provide a whole wetland.
Small habitat claims should name the need being served. A shallow water dish offers water if it is kept clean and safe. A bundle of suitable stems may provide cavities for some bees if it stays dry and is maintained. A container of host plants may feed particular larvae. Bare soil can support ground nesters where pesticide, flooding, traffic, and deep mulch do not defeat it.
Scale does not make these uses false. It makes them specific.
The Steele Street courtyard is small enough that every habitat feature meets human circulation, drainage, public events, walls, and future cat access. Placement determines whether the feature helps wildlife or creates a hunting station, mosquito source, obstruction, or neglected container.
The smallest useful habitat is therefore not the smallest object that can be marketed with the word habitat. It is the smallest maintained condition that a real organism can use without an avoidable trap.
Evaluation requires evidence: signs of use, cleanliness, stability, seasonal timing, and whether the feature remains suitable after weather. Lack of use may mean the site needs time. It may also mean the design serves an imagined animal rather than the local one.
Small habitat work becomes credible when it can state its limit. This pot may shelter. This plant may feed. This patch may permit nesting. None contains an ecosystem, but each can stop one necessary condition from being removed.