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1Clear out junk files and repair common Windows errors2Scan for outdated or missing drivers - takes under a minute3Repair Windows errors before they cause bigger problemsMCP and A2A solve different layers of agent interoperability: MCP connects an agent to tools, APIs, and resources; A2A lets independently built agents communicate and coordinate work. One system can use both—for example, an agent can use MCP to retrieve information, then use A2A to delegate a task to another agent. ACP and ANP help explain how the protocol landscape developed, but they should not be treated as equivalent, independent current alternatives to MCP and A2A.
Why are there so many agent protocols?
“Interoperability” covers several different jobs. An agent may need to call a tool, discover another agent, hand off a long-running task, exchange a result, or establish who it is communicating with. A protocol designed for one of those jobs does not automatically solve the others.
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A useful first cut is agent-to-tool and context versus agent-to-agent coordination. The A2A documentation describes MCP as standardizing how an agent connects to tools, APIs, and resources, while A2A supports communication between agents. The A2A project calls the standards complementary and says they can be used together; its v1.0 release post summarizes the common architecture as MCP inside agents and A2A between agents. That is a helpful model, not a requirement to deploy both. Read the A2A v1.0 documentation and the v1.0 release announcement.
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How do MCP, ACP, A2A, and ANP differ?
The distinctions below combine current A2A project documentation with a survey published May 4, 2025. The survey is useful for understanding the proposals’ original shapes, not for treating every category as an unchanged snapshot of the market. It describes MCP, ACP, A2A, and ANP in a historical comparison; current A2A documentation says IBM ACP was incorporated into A2A. Read the May 2025 survey and check the current A2A documentation.
| Protocol | Primary job | Interaction and discovery | Maturity and governance context |
|---|---|---|---|
| MCP | Connect an agent to tools, APIs, and resources. | The May 2025 survey describes a JSON-RPC client-server interface. The A2A documentation characterizes MCP’s role as agent-to-tool/resource connectivity. | Its relation to A2A is complementary, not winner-take-all. The supplied current A2A sources do not establish MCP’s version status or governance arrangements. |
| ACP | Historically, a proposal for agent messaging. | The May 2025 survey describes REST-native messaging, multipart messages, and asynchronous streaming. | A2A v1.0 documentation says IBM ACP was incorporated into A2A. The survey’s ACP description is historical context, not evidence of a separate current standard with independent status. |
| A2A | Communication and collaboration between agents built with different frameworks or by different vendors. | Its launch-era explanation describes JSON Agent Cards for capability discovery and task handling involving messages, artifacts, task lifecycles, and user-experience negotiation. The v1.0 materials cover protocol bindings and task updates by polling, streaming, or webhooks. | The project announced v1.0 as its first stable version on March 12, 2026. The Linux Foundation reported hosting the project in an April 9, 2026 announcement; a later Axios report said A2A was moving to the Agentic AI Foundation, but the cited sources do not include a primary confirmation of that transfer. |
| ANP | The May 2025 survey presents it as a decentralized approach to agent discovery and collaboration. | That survey describes decentralized discovery using decentralized identifiers and JSON-LD. | Those are survey-era descriptions. The supplied sources do not establish a current stable version, current steward, or current implementation status. |
The table is a map of jobs and evidence, not a quality ranking. A protocol specification also does not guarantee that two products interoperate correctly: implementations still need compatible versions, supported features, and working security and deployment configurations.
What does A2A add between agents?
A2A is an open standard for communication and collaboration between agents developed with different frameworks or by different vendors. It makes agent discovery and task exchange part of the design rather than assuming that all participating agents share one runtime or framework.
Capability discovery through Agent Cards
In Google’s original launch explanation, an Agent Card is a JSON description of an agent’s capabilities and relevant interaction information. It gives a prospective caller a way to discover what an agent offers before assigning it work. Treat that launch post as an explanation of the design at launch, not as the normative implementation reference; use the versioned v1.0 documentation for current requirements. The launch explanation is available from the Google Developers Blog.
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Tasks, messages, and artifacts
The launch-era explanation distinguishes a task from the messages exchanged while carrying it out and from the artifacts produced as results. That distinction is useful in practice: a handoff may take longer than a single request-and-response, and the caller may need progress updates or a deliverable rather than just a short text reply. A2A v1.0 materials describe task updates through polling, streaming, or webhooks. Check the versioned specification for the exact behavior and binding your implementation supports.
Version negotiation and compatibility
The A2A v1.0 release announcement says that v1.0 changes interaction protocol behavior and that earlier v0.3 behavior is not fully backward-compatible. It describes version negotiation and Agent Cards that can advertise support for both behaviors as migration aids. Do not assume a client and server are compatible merely because both say “A2A”: verify their supported protocol versions, bindings, and SDK behavior before connecting them.
How should you think about security and trust?
Interoperability is not the same as trust. A protocol can define ways to describe agents, negotiate versions, or carry messages without deciding which agents an organization should trust, what data they may access, or which actions they may perform. Those decisions remain part of deployment policy and the surrounding identity, authorization, and operational controls.
The A2A v1.0 announcement lists signed Agent Cards and modernized security flows among its changes. Those are relevant protocol features, but they do not by themselves prove that a particular deployment has verified an agent’s identity correctly or granted it appropriate permissions. For an implementation, check the specification’s security requirements and then confirm how the chosen products enforce authorization, protect credentials, and validate capability information.
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In an April 9, 2026 project announcement, the Linux Foundation reported that A2A had support from “more than 150 organizations.” It also reported platform integrations, production deployments, and five production-ready SDK languages. These are dated project-reported figures and claims, not an independent conformance audit or proof that every pair of implementations works together. See the Linux Foundation announcement.
Likewise, the project’s description of v1.0 as stable is evidence about the specification’s release status, not a guarantee that every SDK, service, or integration has the same maturity. The available sources do not provide an independent comparative benchmark for performance, security, implementation cost, or conformance, so those qualities should be evaluated in the intended environment rather than inferred from adoption counts.
How should you choose a protocol for a real system?
Start with the interoperability boundary you need to cross. Avoid choosing from an acronym list before you have identified whether the actual problem is tool access, delegation, discovery, or a combination.
- Write down the interaction. Is an agent calling a tool or resource, or handing work to another agent? MCP is the relevant layer for the former; A2A addresses the latter.
- Describe the lifecycle. Decide whether the exchange is a short call or a task that can run over time and produce progress updates or artifacts. Confirm that the protocol version and implementation support the needed behavior.
- Specify discovery and trust. Establish how the caller finds capability information, verifies the endpoint or agent, and decides what it is authorized to share or request. Do not treat a capability description as authorization.
- Check versions and bindings at both ends. Record the exact specification version, transport or binding, SDK, and supported features for each participant. For A2A, account for the v0.3-to-v1.0 interaction changes and verify version negotiation behavior.
- Test the actual integration. Exercise discovery, successful and rejected requests, long-running updates if needed, error handling, and the security controls in the deployment. A shared protocol name alone is not interoperability evidence.
- Confirm stewardship and support needs. If governance, conformance, or long-term maintenance affects your decision, verify the current official project and governance information rather than relying on older survey descriptions or a dated announcement.
What is the practical takeaway?
Think in layers rather than asking which acronym has won. MCP is for an agent’s connections to tools and context; A2A is for communication and coordination between agents. ACP and ANP remain useful for understanding how the conversation developed, but their May 2025 survey descriptions need current-status qualifications—especially because A2A documentation says IBM ACP was incorporated into A2A. Select only the interfaces your system needs, then validate exact versions, implementations, and trust controls at both ends.
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