AppFunctionsToolset

any Context; only its application context is retained.

the apps whose functions are offered, the calling app by default; null filters nothing and so offers every app's, and an empty set offers none. The nullable mirrors AppFunctionSearchSpec.packageNames, where null likewise means unfiltered and an empty set is rejected. Reaching another app also needs the EXECUTE_APP_FUNCTIONS permission and that this app can see that package; short of that null yields the calling app's own functions and naming an app it cannot see contributes nothing. Executing another app's function can additionally require that this caller be allowlisted.

selects which of the discovered functions the model is shown. It matches the rewritten, model-facing name, not the AppFunction identifier.

whether the guidance an offering app declares about its functions as a whole is added to the model's instructions, on by default -- "app metadata" is the platform's name for that guidance. Turn it off to keep the instructions under the agent's own control, at the cost of the app's advice on how its functions fit together.