Two protocols have settled into the agent ecosystem and they solve different problems. Confusing them creates muddle in architecture decisions.
01. Two Different Axes
MCP standardises the vertical connection: the relationship between an agent and its tools and data sources. A2A standardises the horizontal one: agents talking to each other and handing off work.
02. What MCP Provides
It removes the need to write a separate integration for every tool. Write one MCP server for your ERP and different AI clients can all use it.
03. What A2A Provides
It lets agents from different providers work within the same workflow. Its production use spread quickly in multi-vendor enterprise environments.
04. The Authorisation Question
In both protocols the critical question is the same: under whose identity does the agent act? The user's, or its own service identity? Authorisation can't be designed until that's settled.
05. The Enterprise Meaning
It means investing your integration effort in a standard rather than a single product. When you change your AI tool you don't rewrite the connection layer.
06. Where to Start
Build your first MCP server on a read-only source. Open tools with write access only after authorisation and logging are in place.