The Birth of A2A: How Hermes Learned to Call Other AIs

In March 2026, someone filed a wish on Hermes’s GitHub: let Hermes directly “call” other AIs. Five months later, that wish became an official feature. This wasn’t a big tech company’s top-down decree—it was a house built brick by brick by a dozen community developers passing the baton. Today, Hermes isn’t just an agent that uses tools; it’s an agent that “drops by for a visit.”

The Origin: A “Contact List” for Agents

Think of it this way: the MCP protocol is like a toolbox manual, telling Hermes “which hammers and wrenches you can use.” The A2A protocol is like a contact list, telling Hermes “who lives next door, and who can help you fix the plumbing.” On March 6, 2026, user teknium1 filed wish #514 in the repo: add A2A protocol support to Hermes. The inspiration came from an article about “cybersecurity agent clusters”—which described using MCP as an agent registry and A2A for task delegation, like a company where someone manages the business card holder and someone else handles the phone calls. At the time, Hermes already had a production-grade MCP client—the toolbox manual was thick, but the contact list was empty.

The Journey: Community Relay Race to Build the House

Three months later, on June 8, teknium1 submitted the first integrated plugin (PR #41711), scaffolding the A2A skeleton. That same day, another user, kriszmac4, proposed an official integration plan—like shouting in the neighborhood group chat, “This house is worth building properly.” On June 14, yugui923 added the protocol server (PR #46241), letting Hermes not only “make calls” but also “answer calls.” On June 24, cardinalconseils delivered the most elegant touch (PR #52037): a “business card” (Agent Card) for every agent, placed at /.well-known/agent-card.json, so anyone can visit and learn what the agent can do and how to reach it. The slogan was catchy: “MCP connects agents to tools; A2A connects agents to agents.”

Official Release: v1.0 and the “Herald” Launch

From July to August, the community kept reinforcing: ComicBit added a security peer protocol (PR #63182), kuangmi-bit implemented multi-turn conversations and context persistence (PR #64982). Finally, on August 2, teknium1 submitted the A2A v1.0 release candidate (PR #77109), which passed the official a2a-sdk conformance validation, and the original wish #514 was formally closed. The most impressive part: the entire feature was implemented as a pure plugin, with zero changes to the core code. The next day, Hermes v2026.8.3 “The Herald Release” went live, officially described as “he carries messages to other agents.” This release ships with secure defaults: no token means localhost-only access, per-peer independent keys, prompt injection filtering, signed callbacks with SSRF protection, and a round-limit brake against loops—because even agents chatting with each other need a “don’t talk until the cows come home” cutoff.

Post-Launch Polish: Thirty-Plus Small Fixes

The official release was just the beginning. Over the following weeks, the community submitted over 30 fix and enhancement PRs: long-task timeouts were fixed (#78007/#78357), late-arriving results were no longer dropped (#79721), streaming replies were fully preserved (#83921), context across different conversations was strictly isolated (#83706), audit logs became clearer (#81042), and the system could now identify the real identity behind reverse proxies (#80779). These mundane patches are like changing light bulbs and fixing door locks after moving in—they took A2A from “it works” to “it works well.”

What This Means for Users

Now, if you enable A2A in Hermes, your agent gets its own business card—others can discover it and delegate tasks to it. It can also proactively discover other agents and hand off tasks to more capable “colleagues.” Because A2A is an open protocol governed by the Linux Foundation, Hermes can interoperate with agents from ecosystems like LangChain, CrewAI, and Google ADK. From a wish in March to an official release in August, and now continuous refinement, the most moving part of this story is that it proves AI toolchain evolution can happen like an open-source community—a relay race completed by strangers. Your Hermes now doesn’t just get things done; it makes friends.

📎 Official Release Notes: https://github.com/NousResearch/hermes-agent/releases

📖 Official Documentation: https://hermes-agent.nousresearch.com/docs/user-guide/messaging/a2a