Glossary
A2A
A Google-launched open protocol for agent-to-agent communication, letting agents from different vendors discover each other's capabilities and exchange structured messages.
A protocol that addresses a different problem than MCP. MCPprotocolsAn open protocol from Anthropic that standardizes how language models discover and call external tools, data sources, and prompts via a small JSON-RPC interface.
Open full entry lets a
host application connect a model to tools and data. A2A lets agents
themselves communicate, advertising capabilities and exchanging task
state across vendor and runtime boundaries. The unit of interaction is
agent-to-agent, not model-to-tool.
Google released the initial spec in April 2025 with over 50 partner companies. In June 2025 Google donated A2A to the Linux Foundation, which now stewards the project with AWS, Cisco, Microsoft, Salesforce, SAP, and ServiceNow as founding partners.
Whether A2A and MCP merge, layer, or compete is an open question through 2026. In practice the two coexist: agents use MCPprotocolsAn open protocol from Anthropic that standardizes how language models discover and call external tools, data sources, and prompts via a small JSON-RPC interface. Open full entry to access tools and A2A to coordinate with other agents. MCP plus A2A both reflect a recognition that the agent era needs interop layers it did not need when models were single-turn text APIs.