Amazon announced support for the Agent-to-Agent (A2A) protocol in Amazon Bedrock AgentCore Runtime, enabling communication between agents built on different frameworks. The protocol allows agents developed with Strands Agents, OpenAI Agents SDK, LangGraph, Google ADK, or Claude Agents SDK to “share context, capabilities, and reasoning in a common, verifiable format.” Bedrock AgentCore Runtime serves as the infrastructure layer that processes these inter-agent communications. The A2A protocol introduces interoperability across multi-agent systems, allowing developers to compose workflows that span different agent frameworks.
Agentic systems require several foundational components to operate effectively. Memory functions at two levels: short-term memory maintains conversation context within active sessions, while long-term memory retains insights across multiple sessions over time. Tools provide agents with functional capabilities, accessible either through native integration or via Model Context Protocol (MCP) servers. Identity management enables “more secure authentication and permission management, allowing agents to act on behalf of users or autonomously access resources.” Guardrails implement safety controls designed to “detect harmful content, help prevent hallucinations, and make sure responses align with policies and factual accuracy.”
Source: Bedrock AgentCore Platform
The A2A protocol addresses a different coordination challenge than MCP. While MCP connects a single agent to its tools and data sources, A2A enables multiple agents to coordinate with one another. This distinction matters for system architecture: MCP solves the agent-to-resource connection problem, while A2A solves the agent-to-agent communication problem in multi-agent deployments.
Source: Multi-Agent System Interaction
The A2A protocol implements loose coupling and modularity, allowing each agent to operate as an independent unit. Developers can develop, test, deploy, and upgrade individual agents without disrupting the broader system. New specialized agents can join existing deployments, while agent failures remain isolated within well-defined interaction boundaries.
The protocol includes dynamic agent discovery and orchestration capabilities. Agents advertise their capabilities through standardized schemas, creating a registry of available functions and specializations. Orchestrator agents can then discover and invoke specialized agents based on real-time task requirements, enabling adaptive workflows that route tasks to appropriate agents as conditions change.
The A2A Server, or remote agent, exposes HTTP endpoints that implement the protocol specification. These servers receive requests, process tasks, and return results to calling agents. The architecture supports both synchronous and asynchronous interactions using JSON-RPC 2.0 over HTTP/S or Server-Sent Events.
Each agent publishes an Agent Card, a JSON metadata file that advertises its identity, capabilities, endpoints, and authentication requirements. This metadata enables the dynamic discovery mechanism, where agents query peer agents to determine their capabilities before delegating tasks. The Agent Card serves as a contract specification, providing other agents with the information needed to interact correctly with the publishing agent.
The Task Object represents each unit of work flowing through the system. Each task carries a unique identifier and maintains its own lifecycle as it moves between agents. Tasks can be long-running operations that involve multiple interaction turns and span several agents working together. The protocol tracks task state as agents coordinate, allowing orchestrator agents to monitor progress and handle failures or timeouts across distributed agent collaborations.
Regarding the community reaction to this announcement, Unit42 by Palo Alto Networks identified potential vulnerabilities in the protocol’s stateful design. According to Unit42’s analysis,
The A2A protocol’s stateful behavior lets agents remember recent interactions and maintain coherent conversations. Session smuggling attack exploits this property to inject malicious instructions into a conversation, hiding them among otherwise benign client requests and server responses.
Developers interested in implementing A2A-based systems can access several technical resources to begin working with the protocol. The Amazon Bedrock AgentCore Developer Guide provides comprehensive documentation covering runtime operations, memory management, and identity handling across agent deployments. The A2A protocol contract specification defines the technical requirements for implementing agent-to-agent communication and interaction patterns that conforming agents must support. InfoQ’s earlier coverage of the Bedrock AgentCore announcement provides additional context on the platform’s initial capabilities.
