Google's agent SDK in Python, Java, Go, and TypeScript. Docs now live at google.github.io/adk-docs. A2A is a separate protocol repo.

A2A is an open agent-to-agent communication protocol under the Linux Foundation, built on Agent Cards, tasks, and messages and complementing MCP.

An open, vendor-neutral standard for internet-native payments over HTTP, allowing agents to pay for resources directly through 402 Payment Required responses.

Agentry is an Apache-2.0 AMTP gateway that runs AI-generated multi-agent workflows and stores organizational decision traces.