The friction of agents having to monitor CLI is just too annoying right now
Thus, this is ultimately:
1. a harness problem (or harness orchestrator)
2. a protocol problem
With 1. Claude Code does this very well - yet most OSS harness are not great or do naive subagent tasking making hard even for a parent to talk to the child. But we can then rely on harness orchestrators - Herdr does this very well, so does the Codex app - which counts here due to how it spins up entire threads that another can manage. Any thread can talk to each other on these orchestrators - herdr is fun.With 2. we require native adapters in clients. MCP has the necessary things coming down the chain to enable real integrated push events to agents. Push events means bi-directional in-and-out of the agent.
Look to build your tooling in MCP once it lands! Just sharing my opinion, having built something similar last year. https://github.com/eqtylab/real-a2a