What it does
The Agent-to-Agent protocol standard that defines how AI agents communicate, authenticate, and collaborate. Specifies the message formats, security boundaries, and trust models for multi-agent systems.
Security relevance
As multi-agent systems proliferate, the communication layer between agents becomes a critical attack surface. A2A Protocol defines how agents establish trust, authenticate requests, and maintain security boundaries — preventing one compromised agent from manipulating others. CB Insights confirms all three major cloud providers (Amazon, Google, Microsoft) have adopted A2A for agent interoperability, making it a de facto standard. The OWASP Agentic Top 10 identifies A2A registration spoofing and Agent-in-the-Middle attacks as key ASI07 threats.
When to use it
Implement when building multi-agent systems where agents need to communicate securely. Requires protocol implementation, identity management, and security boundary design. Expert-level architecture work but essential for any production multi-agent deployment.
OWASP coverage
Risks addressed — mapped to both OWASP Top 10 standards. 2 in LLM, 1 in Agentic.
The raw record
What Yuntona stores. Single source of truth — fork it on GitHub.
name: A2A Protocol slug: a2a-protocol type: Mixed category: AI Guardrails & Firewalls url: https://a2a-protocol.org/latest reviewed: 2026-04 added: 2026-04 updated: 2026-04 risks: llm: [LLM07, LLM08] asi: [ASI07] complexity: Expert Required pricing: — audience: Builder lifecycle: [deploy] tags: [Agents, Protocol, Standard]