AI Insights · Oct 23, 2026 · Partially verified
Three agent protocols, three jobs
ACP links editors to agents, A2A 1.0 links agents to each other, and AG-UI links agents to the people using them. All three are now governed by the Linux Foundation's Agentic AI Foundation.
Claim
Three protocols cover three edges: ACP connects editors to agents over stdio (Claude Code, Codex CLI, Copilot CLI, Gemini CLI, OpenCode in the registry), A2A 1.0 connects agents to agents with signed agent cards and webhook push, and AG-UI streams agent state to a UI. MCP, AGENTS.md, goose and A2A are now all under the Agentic AI Foundation with Anthropic, OpenAI, Google, Microsoft, AWS and others as platinum members.
Evidence
- ACP: JSON-RPC 2.0 over stdio, protocol version integer 1, capabilities for session load, compaction, elicitation, client filesystem and terminal; remote agents over HTTP or WebSocket "still in progress". The ACP Registry (2026-01-28) lets an agent register once for Zed and JetBrains.
- A2A 1.0: three functionally equivalent bindings (JSON-RPC, gRPC, HTTP+JSON), signed Agent Cards, opaque tenant field, webhook push, task states including INPUT_REQUIRED and AUTH_REQUIRED. Over 150 organisations, five SDKs, native support in Azure, Bedrock AgentCore and Google Cloud. Exact 1.0 release date UNVERIFIED. Joined AAIF 2026-08-27.
- AG-UI: event protocol over HTTP or WebSockets; first-party integrations with Microsoft Agent Framework, Google ADK, AWS Strands, Pydantic AI and Mastra; community adapters for Claude Agent SDK and Managed Agents.
- AAIF founded 2025-12-09 with MCP, goose and AGENTS.md; A2A added August 2026; Envoy AI Gateway renamed Agent Router September 2026. ACP remains vendor-stewarded. Agent Skills was too until 2026-10-22, when Anthropic donated it to AAIF (changed 2026-10-23, see [[2026-10-agent-skills-donated-to-aaif]]); the earlier line "Agent Skills and ACP remain vendor-stewarded" is no longer true for Skills.
Open questions
- Whether AG-UI or MCP Apps wins for interactive UI from agents.
Sources
- https://agentclientprotocol.com/protocol/initialization — spec, Wed Oct 21
- https://zed.dev/blog/acp-registry — blog, Tue Jan 27
- https://a2a-protocol.org/latest/specification/ — spec, Wed Oct 21
- https://a2a-protocol.org/latest/blog/2026/08/27/a-new-chapter-for-a2a-joining-the-agentic-ai-foundation/ — blog, Wed Aug 26
- https://docs.ag-ui.com/introduction — docs, Wed Oct 21
- https://linuxfoundation.org/press/linux-foundation-announces-the-formation-of-the-agentic-ai-foundation — press, Mon Dec 08
- https://www.anthropic.com/news/donating-agent-skills-to-the-agentic-ai-foundation — blog, Wed Oct 21
AI-assisted research: gathered and summarised with AI from the sources above, each claim checked against them.