A2A Protocol Interoperability
Parent: AI Agent Ecosystems · Published reference · snapshot 2026-09-08 · skill ai-agents-orchestration/references/a2a-interop.md
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Reference for the Agent-to-Agent protocol and cross-framework agent communication.
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A2A Protocol & Agent Interoperability
- Reference for the Agent-to-Agent protocol and cross-framework agent communication. [archived source: https://llms-explorer.com/sources/mdb-context-hub/a2a-interop/#a2a-protocol-agent-interoperability]
When to use this skill
- Activate when the user: [archived source: https://llms-explorer.com/sources/mdb-context-hub/a2a-interop/#when-to-use-this-skill]
- asks about the A2A protocol or agent-to-agent communication [archived source: https://llms-explorer.com/sources/mdb-context-hub/a2a-interop/#when-to-use-this-skill]
- wants to publish an Agent Card at .well-known/agent.json [archived source: https://llms-explorer.com/sources/mdb-context-hub/a2a-interop/#when-to-use-this-skill]
- needs to implement A2A task lifecycle handling [archived source: https://llms-explorer.com/sources/mdb-context-hub/a2a-interop/#when-to-use-this-skill]
- asks how A2A and MCP work together [archived source: https://llms-explorer.com/sources/mdb-context-hub/a2a-interop/#when-to-use-this-skill]
- wants cross-framework agent interop (LangGraph <-> CrewAI <-> ADK <-> Claude SDK) [archived source: https://llms-explorer.com/sources/mdb-context-hub/a2a-interop/#when-to-use-this-skill]
- asks about AAIF, ACP, ANP, or agent protocol governance [archived source: https://llms-explorer.com/sources/mdb-context-hub/a2a-interop/#when-to-use-this-skill]
- needs to design a multi-vendor agent system [archived source: https://llms-explorer.com/sources/mdb-context-hub/a2a-interop/#when-to-use-this-skill]
Core JSON-RPC operations
- Required header: A2A-Version: Major.Minor in all requests. [archived source: https://llms-explorer.com/sources/mdb-context-hub/a2a-interop/#core-json-rpc-operations]
Governance (2026)
- AAIF (Agentic AI Foundation, Linux Foundation): neutral governance body for A2A and MCP. [archived source: https://llms-explorer.com/sources/mdb-context-hub/a2a-interop/#governance-2026]
- ACP: merged into A2A under AAIF. [archived source: https://llms-explorer.com/sources/mdb-context-hub/a2a-interop/#governance-2026]
- ANP: emerging decentralized peer-to-peer discovery layer above A2A. [archived source: https://llms-explorer.com/sources/mdb-context-hub/a2a-interop/#governance-2026]
References
- A2A Protocol Specification [archived source: https://llms-explorer.com/sources/mdb-context-hub/a2a-interop/#references]
- A2A GitHub Repository [archived source: https://llms-explorer.com/sources/mdb-context-hub/a2a-interop/#references]
Where this helps
- Designing a multi-vendor agent system where agents built on different frameworks (LangGraph, CrewAI, ADK, Claude SDK) need to discover each other's capabilities and hand off tasks. [source] — AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.
- Publishing an Agent Card at .well-known/agent.json so external agents or orchestrators can discover what an agent can do before invoking it. [source] — AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.
- Deciding whether a cross-agent interaction belongs on A2A (agent-to-agent task handoff) versus MCP (agent-to-tool/data access) when the two protocols overlap in a system design. [source] — AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.
- Tracking protocol governance changes (AAIF, ACP's merge into A2A, ANP's peer-to-peer discovery layer) before committing to a long-term multi-agent architecture. [source] — AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.
Project ideas
- Publish an Agent Card at .well-known/agent.json for an existing agent so it becomes discoverable to other A2A-compliant orchestrators. [source] — AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.
- Build a task-lifecycle handler that speaks A2A's JSON-RPC operations, including the required A2A-Version header, so a LangGraph agent can hand off a task to a CrewAI agent. [source] — AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.
- Prototype an ANP-based peer-to-peer discovery layer on top of an existing A2A deployment to let agents find each other without a central registry. [source] — AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.
- Wire an agent that already exposes MCP tools so it also exposes an A2A Agent Card, giving it both a tool-consumption and an agent-collaboration surface. [source] — AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.
Antipatterns
- Treating A2A and MCP as interchangeable — MCP is for agent-to-tool/data access, A2A is for agent-to-agent task handoff, and conflating the two produces the wrong integration surface. [source] — AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.
- Omitting the required A2A-Version header on JSON-RPC requests, which breaks version negotiation between agents built by different teams. [source] — AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.
- Building a bespoke discovery mechanism for a multi-framework agent system instead of publishing a standard Agent Card at .well-known/agent.json. [source] — AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.
- Assuming ACP is still a separate protocol to integrate against, when it has already merged into A2A under AAIF governance. [source] — AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.
Known issues
- ACP and ANP are still consolidating under AAIF governance as of 2026, so protocol boundaries and long-term ownership can still shift. [source] — AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.
- ANP's decentralized peer-to-peer discovery layer sits above A2A but is described as emerging, so it's less mature than the core A2A task lifecycle. [source] — AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.
- Cross-framework interop (LangGraph, CrewAI, ADK, Claude SDK) depends on each framework's own A2A adapter staying current with the spec, which is an extra maintenance surface beyond the protocol itself. [source] — AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.
- This pack's own sourced content is thin — mostly trigger conditions and a governance summary — so treat it as a starting map rather than a full protocol reference; read the linked A2A Protocol Specification for wire-level detail. [source] — AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.
Children
- 7-State Task Lifecycle
- AAIF and Protocol Governance
- Agent Cards (frontier)
- JSON-RPC 2.0 Transport (frontier)
- Cross-Framework Agent Bridging (frontier)
Frontier under this node: Agent Cards, Cross-Framework Agent Bridging, JSON-RPC 2.0 Transport