What is A2A (Agent-to-Agent)?
A protocol for AI agents to discover and communicate with each other, exchanging messages through published capability descriptions called AgentCards.
As organizations deploy multiple AI agents, those agents need a standard way to find and use each other — a customer-service agent delegating a billing question to a billing specialist, or an external agent querying a vendor's knowledge agent.
A2A handles this with two pieces: an AgentCard, a public JSON description of what an agent can do and where to reach it, and a message protocol (message/send) for the actual exchange. Where MCP connects an assistant to tools, A2A connects agents to agents.
How BeforeQuery uses this
Each knowledge base publishes a public A2A AgentCard and accepts message/send calls (client-key authenticated), so external agents can query your knowledge programmatically. The @beforequery/agents SDK includes both A2A and MCP clients, and A2A calls appear in traces.
Related terms
MCP (Model Context Protocol)
An open protocol that lets AI applications (like IDE assistants) connect to external tools and data sources through a standard JSON-RPC interface.
LLM Gateway
An abstraction layer between an application and language-model providers, allowing models to be swapped, routed, and managed without changing application code.
Knowledge Base
A curated, indexed collection of an organization's knowledge — docs, wikis, tickets, repos — that an AI assistant retrieves from when answering questions.
From definition to deployment
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