// GLOSSARY -- AGENTIC AI

What is an Agent Protocol?

1 min read Updated

An agent protocol is a standardized specification for how AI agents communicate, discover capabilities, exchange data, and coordinate actions — enabling interoperability between agents built with different frameworks and by different developers.

WHY IT MATTERS

Without protocols, every agent integration is custom. Agent A built with LangGraph can't talk to Agent B built with CrewAI unless someone writes glue code. Protocols solve this by defining common interfaces.

The emerging protocol landscape includes MCP (Model Context Protocol) for agent-to-tool communication, A2A (Agent-to-Agent Protocol by Google) for inter-agent communication, and x402 for agent payments. Each addresses a different interaction type.

Protocol adoption creates network effects. Once enough agents and tools support MCP, the ecosystem becomes self-reinforcing — new tools automatically work with existing agents, and new agents automatically access existing tools.

HOW POLICYLAYER USES THIS

PolicyLayer supports standard agent protocols for financial interactions. Whether agents communicate via A2A, access tools via MCP, or make payments via x402, PolicyLayer enforces spending policies at the protocol level.

FREQUENTLY ASKED QUESTIONS

What are the main agent protocols?
MCP (Model Context Protocol) for agent-to-tool interaction, A2A (Agent-to-Agent) for inter-agent communication, x402 for agent payments, and the original Agent Protocol specification for basic agent API standardization.
Do I need to implement all agent protocols?
No. Start with what you need. MCP is the most widely adopted for tool integration. A2A matters if you're building multi-agent systems across organizational boundaries. x402 matters for agent payments.
Are agent protocols mature enough for production?
MCP is rapidly maturing with broad adoption. A2A and x402 are newer but usable. The landscape is still evolving — expect protocol consolidation and standardization over the next 1-2 years.

FURTHER READING

Enforce policies on every tool call

Intercept is the open-source MCP proxy that enforces YAML policies on AI agent tool calls. No code changes needed.

npx -y @policylayer/intercept
github.com/policylayer/intercept →
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