Agent2Agent Protocol
An open protocol that lets one AI agent hand work to another agent it did not build, so an IBM i shop can keep its Db2 for i tools behind its own agent and still let an outside agent ask that agent for an answer. Google published it in April 2025 and gave it to the Linux Foundation on June 23, 2025; IBM's watsonx Orchestrate connects external A2A agents, and IBM's ContextForge MCP Gateway federates A2A servers beside Model Context Protocol servers.
What Agent2Agent does
Agent2Agent, or A2A, is a shared set of rules for one AI agent to ask another AI agent to do a job. The two agents can come from different vendors and can be written in different languages. Neither one has to open up its code or share its tools. Think of a general contractor and a plumber. The contractor does not borrow the plumber's wrench. The contractor hands over the job, waits, and takes the finished work. A2A is the paperwork that makes that handoff the same every time.
How is it different from MCP?
Model Context Protocol, or MCP, is how one AI reaches a tool, such as a query against Db2 for i. A2A is how one agent reaches another agent. IBM calls the two complementary, and they often run side by side in the same setup.
MCP and A2A side by side
| Question | MCP | A2A |
|---|---|---|
| What is on the other end? | A tool, a data source or a function | Another agent that can plan and decide |
| Who answers? | A server you register | An agent that publishes an Agent Card |
| What comes back? | A tool result | A Task that ends in Artifacts |
| Typical IBM i role | Your Db2 for i and system tools, exposed through Mapepire | An outside agent asking your agent for an answer |
IBM's ContextForge MCP Gateway federates both, plus plain REST and gRPC services, behind one endpoint.
How does one agent call another?
An A2A handoff, start to finish
- Read the Agent CardThe calling agent fetches a small JSON file that names the other agent, its endpoint, what it can do, and how to log in.
- Send a TaskThe job goes over as a Task with its own identifier. It can carry text, files or structured JSON data.
- Watch the TaskA Task moves through submitted, working, input-required, completed and failed. Updates arrive live over server-sent events, or later through a webhook the caller supplies.
- Collect the ArtifactsFinished output comes back as Artifacts, such as a document or a spreadsheet, and can stream back in pieces.
All of it rides on HTTPS using JSON-RPC 2.0, which is a plain way to send a request and a reply as JSON.
Can an IBM i shop use it?
Not inside IBM i. A2A is spoken where the agents run, which for most shops is a Linux partition or a cloud service. The IBM i side of the job is the same work MCP already covers: expose your Db2 for i data and system tasks as tools, reached over the network through Mapepire. A2A sits one floor up. IBM's watsonx Orchestrate is the clearest route today, because it can register an outside agent as an external A2A agent and delegate work to it.
Check versions before you wire anything up. The published specification is at v1.0.1, but IBM's watsonx Orchestrate documentation says the supported A2A version is 0.3.0, that earlier versions such as 0.2.1 are deprecated, and that its support is limited to JSON-RPC 2.0 over HTTP even though A2A allows other transports.
Agent2Agent timeline
- Mar 25, 2025Google creates the A2A specification repository on GitHub under the Apache 2.0 license.
- Apr 2025Google introduces the Agent2Agent protocol publicly.
- Jun 23, 2025Google donates the specification, SDKs and tooling to the Linux Foundation at Open Source Summit North America. The Agent2Agent project forms with Amazon Web Services, Cisco, Google, Microsoft, Salesforce, SAP and ServiceNow.
- Jul 30, 2025Version 0.3.0 ships. This is still the version IBM's watsonx Orchestrate documents today.
- Mar 12, 2026Version 1.0.0 ships.
- May 28, 2026Version 1.0.1 ships, the current release.
Google's June 2025 donation post said more than 100 companies supported the protocol at that point. That count is Google's own.
Related Terms
Model Context Protocol
An open standard, released by Anthropic on November 25, 2024, that defines a client-server architecture for connecting AI applications to external data sources, tools, and prompts over JSON-RPC 2.0. IBM's IBM i MCP Server is an implementation of it for Db2 for i and other IBM i resources.
ContextForge MCP Gateway
IBM's open source gateway that puts one governed endpoint in front of every Model Context Protocol server, so an IBM i shop can register its Db2 for i tools once and let any AI client reach them with shared login checks, rate limits and logging. IBM's own IBM i MCP Server project ships a container stack that runs the gateway on port 4444 beside an IBM i SQL tools server on port 3010.
watsonx Orchestrate
IBM's AI agent and automation platform for orchestrating multi-step business workflows across enterprise applications. Since August 2026 it can launch IBM Bob from its Create an agent dialog through a Build with Bob preview, but it still ships no IBM i or Db2 for i connector.
watsonx Orchestrate Agent Builder
watsonx Orchestrate Agent Builder is where an AI agent is actually defined: its name, its written instructions, the large language model that reasons for it, and the list of tools it is allowed to call. For an IBM i shop the tool list is the whole story, because it accepts a Model Context Protocol (MCP) toolkit, and that is the practical way to point an Orchestrate agent at Db2 for i data when IBM ships no IBM i connector.
IBM i MCP Server
An open-source, IBM-published server implementing the Model Context Protocol (MCP), letting AI agents and LLMs query Db2 for i data and take defined actions on IBM i using natural language. In beta since October 2025.
Mapepire
An open-source database access layer for Db2 for i, created by IBM and introduced in an August 2024 IBM blog post as a lighter, cloud-friendly alternative to ODBC and JDBC. A server daemon runs on IBM i and Node.js, Python, Java, and .NET Core clients connect to it over Secure WebSockets.
Db2 for i
The relational database management system built into every IBM i operating system, tightly integrated with IBM i rather than a separately installed database product.
IBM i
IBM's operating system for Power servers running traditional AS/400-lineage business applications, with Db2 for i built directly into the OS.