MCP vs A2A: the two protocols behind the agent economy
MCP and A2A solve different problems. The Model Context Protocol (MCP), created by Anthropic and now governed by the Linux Foundation’s Agentic AI Foundation, connects an AI agent to tools and data. The Agent2Agent protocol (A2A), launched by Google in 2025 and now a Linux Foundation project, lets agents from different vendors discover each other, share tasks and exchange results. Most multi-agent systems will use both: MCP for tools, A2A for agent-to-agent collaboration.
What are MCP and A2A?
As businesses deploy more AI agents, two kinds of connection matter. An agent needs to reach tools and data, such as a CRM, a database or a file store. And agents increasingly need to work with other agents, often built by different vendors. MCP standardises the first; A2A standardises the second. Our guide to multi-agent systems explains why teams of agents are emerging.
How do they fit together?
Each agent uses MCP to reach its own tools. A2A carries the requests and results between agents. Neither replaces the other.
How does A2A work?
- Agent cards: Each agent publishes a description of its skills, endpoint and authentication needs.
- Discovery: A client agent finds a suitable remote agent from its card.
- Task creation: The client sends a task with the details needed.
- Progress and messages: Agents exchange updates, questions and partial results while the task runs.
- Artifacts: The remote agent returns results, such as documents or data, when done.
According to the Linux Foundation, more than 150 organisations supported A2A within its first year, and it is integrated into major cloud platforms.
Who supports them?
| MCP | A2A | |
|---|---|---|
| Origin | Anthropic, November 2024 | Google, April 2025 |
| Governance | Agentic AI Foundation, Linux Foundation | Linux Foundation project |
| Typical users | Assistants, IDEs, agent frameworks | Enterprise agent platforms and clouds |
| Maturity | Widely deployed; major revision July 2026 | Growing; early production use |
Which does your business need?
For most organisations today, MCP is the priority: connecting assistants and agents to the systems where work lives. A2A becomes important when you run agents from several vendors, for example a CRM vendor’s agent, a support platform’s agent and your own, and want them to cooperate without custom integration.
What about other agent protocols?
MCP and A2A are not the only standards. In commerce, protocols such as the Agentic Commerce Protocol and Agent Payments Protocol handle checkout and payment consent, as covered in what is agentic commerce. On the web, proposals such as WebMCP aim to let websites offer structured tools to browser agents. Most of these build on the same ideas: describe capabilities clearly, authenticate every party and keep a person in control of consequential actions. For a business, the practical approach is to adopt the standards your vendors and platforms support, rather than betting early on niche ones.
What does a real cross-vendor example look like?
Imagine a company running a CRM vendor’s sales agent, a helpdesk vendor’s support agent and its own internal finance agent. A customer asks to upgrade their plan. The sales agent, through A2A, asks the support agent whether the customer has open issues, and asks the finance agent for an approved discount. Each agent uses MCP to reach its own systems: the CRM, the helpdesk and the billing database. The sales agent combines the answers into an offer, and an account manager reviews it before it goes out. Without A2A, someone would have to build custom integrations between three vendors’ agents; without MCP, each agent would need bespoke connections to its tools.
How should a business prepare?
- Start with MCP: Connect your main assistants and agents to core systems.
- Inventory your agents: List agents from vendors and your own builds, with owners.
- Check vendor support: Ask whether each platform supports MCP and A2A.
- Define trust rules: Decide which agents may ask others for help, and with what data.
- Pilot one hand-off: Test a single cross-agent task with human review before scaling.
What are the risks?
- Every connection, between tools or agents, widens the attack surface
- Trust between agents needs authentication and clear permissions
- Errors can pass from one agent to another and compound
- Accountability is harder when several agents contribute to one outcome
- Standards are still evolving, so expect changes
Keep people approving important outcomes, as covered in human-in-the-loop AI, and see MCP security risks.
How UIUX Studio helps
We design agent architectures that use MCP and A2A where they add value, with approvals and monitoring built in. Talk to our Agentic AI & Automation and product engineering teams.
Frequently asked questions
Is A2A a competitor to MCP?
No. MCP connects agents to tools; A2A connects agents to each other.
Who created A2A?
Google launched it in April 2025; it is now a Linux Foundation project.
Who governs MCP?
The Agentic AI Foundation, a directed fund under the Linux Foundation.
Do I need A2A today?
Only if you run agents from several vendors that need to cooperate.
Can one agent use both?
Yes. It can use MCP for its tools and A2A to work with other agents.