AI protocols explained: MCP, A2A and what they mean for your business

What is an AI protocol?

An AI protocol is an agreed standard for how AI systems exchange information: how an agent discovers what a tool can do, how it asks the tool to act and how it gets the result back. It plays the same role for AI that HTTP plays for websites, or that USB-C plays for chargers: build to the standard once, and many things can connect.

Without a protocol, every connection between an AI model and a business system is custom code. With one, a tool built once can serve many agents, and you can change the AI model without rebuilding every integration.

The two protocols that matter most today are the Model Context Protocol (MCP), which connects agents to tools and data, and Agent2Agent (A2A), which connects agents to each other.

Model Context Protocol (MCP)

MCP is an open standard that Anthropic introduced in November 2024 for connecting AI applications to external tools and data. In December 2025, Anthropic donated MCP to the Agentic AI Foundation, a fund under the Linux Foundation that it co-founded with OpenAI and Block, so no single company controls it.

MCP uses a client and server model:

• MCP servers expose what a system can do: tools the agent can call, resources such as files or records it can read, and prompts, which are reusable instructions.
• MCP clients live inside the AI application, such as an assistant or an agent platform, and connect to one or more servers.

Support is broad. Microsoft Copilot Studio, for example, lets you add an MCP server to an agent as a tool, and many software vendors now publish MCP servers for their products.

What MCP means for your business

• Faster integrations: if your software has an MCP server, an agent can often use it without custom code
• Less lock-in: change the AI model without rebuilding every connection
• Reuse: one MCP server for your CRM can serve your sales agent, your support agent and your internal assistant

Agent2Agent protocol (A2A)

A2A is an open protocol for AI agents to find each other, share tasks and exchange results, even when different vendors built them. Google started it in April 2025, and it is now run under the Linux Foundation. In August 2025, IBM's Agent Communication Protocol (ACP) merged into A2A.

Each A2A agent publishes an agent card that describes what it can do. Other agents read the card, send it a task and follow the task until it is done. That is how a booking agent from one vendor could hand a job to a payments agent from another.

MCP vs A2A: what is the difference?

They are complementary, not competing. A common pattern is an agent that uses MCP to reach its tools and A2A to work with other agents.

Are AI protocols secure?

A protocol is only as safe as the way it is used. MCP servers can take real actions, so treat each one like software with access to your systems:

• Use servers from sources you trust, and review what each tool can do
• Give each server the minimum access it needs, with proper sign-in such as OAuth
• Watch for prompt injection, where text in a document or web page tries to give the agent instructions
• Require a person's approval for actions such as payments or deleting data
• Log every tool call, and handle personal information in line with POPIA

Do you need MCP or A2A to build an AI agent?

No. Many useful agents connect to systems directly through APIs or built-in connectors. Protocols become valuable as you add more tools, more agents and more AI platforms.

When we build an AI agent, we connect it to your systems in the way that suits them: a standard protocol such as MCP where your tools support it, and a direct API connection where they do not.

New to agents? Start with our guide on how to build an AI agent.

Looking for an AI usage protocol for your staff?

Some people use AI protocol to mean the rules staff follow when they use AI tools at work. That is an AI usage policy. Our Microsoft Platform and AI Training covers using Copilot and other AI tools safely with company data, a good starting point for that policy.