ConstEvery host surface generates its registrations from this list. A capability that appears on one surface and not another is a bug, not a decision — affordances are expected to differ, capabilities are not.
Structural reads are deliberately NOT tools: run -e "<expression>" --md renders any SDK
object through the renderer registry, so a describe verb would be a second copy of what
code already expresses (a describe tool was built and removed 2026-07-30 for exactly this
reason). A capability joins this list only when it is not a one-line run idiom.
The read surface, defined once.