First time I found this was in Google A2A protocol: https://developers.googleblog.com/en/a2a-a-new-era-of-agent-interoperability/ https://developers.googleblog.

First time I found this was in Google A2A protocol: https://developers.googleblog.com/en/a2a-a-new-era-of-agent-interoperability/ https://developers.googleblog.com/en/a2a-a-new-era-of-agent-...