When true (the default), the capabilities advertised at initialize
(and in every draft per-request _meta) are derived from which handlers
are installed: onSampling implies sampling, onElicitation implies
elicitation (form submode), onListRoots implies roots. Anything
already set on capabilities is preserved (e.g. submodes, listChanged,
tasks), so this only ever adds the presence flags a handler implies and
never clears an explicit advertisement. Set to false to advertise exactly
capabilities and nothing more (the explicit-override escape hatch).
When true (the default), the capabilities advertised at initialize (and in every draft per-request _meta) are derived from which handlers are installed: onSampling implies sampling, onElicitation implies elicitation (form submode), onListRoots implies roots. Anything already set on capabilities is preserved (e.g. submodes, listChanged, tasks), so this only ever adds the presence flags a handler implies and never clears an explicit advertisement. Set to false to advertise exactly capabilities and nothing more (the explicit-override escape hatch).