ACA vs MCP

A2A vs MCP: Comparing AI Standards for Agent Interoperability

As AI agents increasingly automate and enhance complex workflows, the technology landscape is seeing the rise of crucial interoperability standards. Google's Agent2Agent (A2A) protocol and Anthropic's Model Context Protocol (MCP) stand out as prominent initiatives that, while complementary, target distinct aspects of AI integration. Here we take a deeper look at both, examining their designs, adoption trajectories, and broader strategic implications.

Technical Architectures

Agent2Agent (A2A) – Google’s Agent2Agent (A2A) protocol is an open application-layer standard for multi-agent communication and collaboration. It enables independent AI agents (regardless of vendor or framework) to communicate, coordinate tasks, and share context in a standardized way. A2A defines a client–remote agent model: a client agent formulates tasks on behalf of a user, and a remote agent acts on those tasks to provide information or perform actions. Communication is structured around Tasks – units of work with defined lifecycles and outputs (called “artifacts”) – and message exchanges. Each agent advertises its capabilities via an Agent Card (a JSON metadata file), which allows dynamic capability discovery so a client agent can find the best remote agent for a given job. Messages between agents carry context, results, or instructions and are composed of Parts (e.g. text, data, or file content) to support rich multimodal interactions. Notably, A2A is built on familiar web standards (HTTP, Server-Sent Events, JSON-RPC) for easy integration into existing systems. It’s designed to be secure-by-default with enterprise-grade authentication (aligning with OpenAPI auth schemes), and supports long-running processes with real-time status updates (agents can keep a task “open” for hours/days as needed). A2A is also modality-agnostic – beyond text, it can stream audio or video – enabling agents to negotiate the best format for information exchange based on each other’s UI or capabilities (e.g. an agent can request a chart or form when appropriate). In essence, A2A provides a common language and protocol for heterogeneous agents to collaborate without sharing memory or internal tools directly, by passing messages and artifacts over a secure, standardized interface.

Model Context Protocol (MCP)Anthropic’s Model Context Protocol takes a different but complementary approach: MCP is an open standard to connect AI models/assistants with external data sources and tools in a uniform way . Often described as a “USB-C for AI applications,” MCP defines a plug-and-play interface for providing context to language models. Its architecture follows a client–server paradigm: An AI application (LLM-powered assistant, agent, IDE, etc.) acts as an MCP client, which connects to one or more MCP servers. Each MCP server is a lightweight connector that exposes a specific data source or service (e.g. a database, a filesystem, an API) through the MCP standard. The servers offer tools or data that the model can use, and the MCP client can query these servers in a standardized way. This allows an AI agent to retrieve information or execute actions on external systems securely, without custom integration code for each tool. MCP interactions are two-way and real-time: an assistant can call a tool (via the server) and get results to incorporate into its responses, and servers can handle authentication (e.g. OAuth for remote APIs) and enforce access controls. Key concepts in MCP include Tools (model-invoked operations like searching a knowledge base or writing to a file), Resources (data provided by the application, like specific files or JSON payloads given to the model), and Prompts (pre-defined prompt templates or commands). By standardizing how these are described and invoked, MCP enables dynamic tool discovery and usage – an AI agent can learn what tools are available at run-time and invoke them as needed, rather than being pre-programmed for each . The protocol supports both local connectors (running as subprocesses for local data) and remote connectors (accessed over HTTP + Server-Sent Events). Importantly, MCP emphasizes security and flexibility: companies can expose internal data through MCP servers under their control (keeping data within existing infrastructure), and only approved tools are available to the model. In summary, MCP focuses on providing AI agents with the context and capabilities they need (from databases, files, APIs, etc.) via a unified, open interface, so that one standard integration can replace dozens of bespoke plugins.

Integration and Complementarity: A2A and MCP address different layers of the AI agent stack. A2A is about agent-to-agent interaction, whereas MCP is about agent-to-system/tool integration. They are designed to be complementary – in fact, Google explicitly positions A2A as “an open protocol that complements Anthropic’s MCP”. In practice, an enterprise could use A2A for orchestrating multiple agents (each possibly with different specialties or from different vendors) that collaborate on a complex task, while using MCP to let those agents securely tap into external tools and data sources as needed. Both protocols are open-source and framework-agnostic, enabling them to be integrated together: for example, a Google Cloud agent built with A2A can fetch company data via an MCP connector to fulfill part of a task. This interoperability shows in tooling – Google’s own Agent Development Kit (ADK) supports MCP for connecting agents to data, alongside A2A for agent collaboration.

Adoption Trends

Agent2Agent (A2A) Adoption: A2A is very new (launched in April 2025) but has garnered significant industry attention out of the gate. Google introduced A2A with support from 50+ partner companies and immediately open-sourced the draft specification and sample implementations. This broad coalition at launch suggests a concerted push for adoption across enterprise software platforms. Because A2A is open and language-agnostic, developers quickly showed interest – the public A2A repository gained over 5,000 stars on GitHub within days, indicating enthusiasm and curiosity from the developer community. Google’s own ecosystem is integrating A2A: for example, A2A is being incorporated into Google Cloud’s Vertex AI platform and ADK for building multi-agent systems. Early adoption is largely in proof-of-concept and exploratory stages given how new the protocol is. However, the presence of agent framework builders like LangChain among the partners suggests that soon A2A could be implemented in popular agent development libraries, enabling wider developer uptake. Enterprise software partners (Salesforce, ServiceNow, etc.) are likely to roll out A2A compatibility in their AI offerings, which would rapidly expand usage within enterprise environments. In short, while concrete deployments are just beginning, A2A’s adoption trajectory is bolstered by strong enterprise backing and immediate community interest, positioning it to become a standard “lingua franca” for agent communication if momentum continues.

Model Context Protocol (MCP) Adoption: Since its release (open-sourced in late 2024), MCP has seen fast-growing adoption among developers and certain forward-looking companies. Its open-source repositories have become highly active: the main MCP server repository (which hosts reference connectors) has 34k+ stars on GitHub and dozens of community-contributed servers, indicating widespread developer engagement in a short time. A vibrant community has built MCP integrations for many systems – by early 2025 there are connectors for Google Drive, Slack, GitHub, databases like Postgres, web search APIs, and more. This growing library of pre-built integrations validates MCP’s value: instead of each AI app writing custom code for each tool, developers can reuse community connectors via MCP. Several developer-focused products have adopted MCP. IDE and coding assistant tools such as Cursor and Zed use MCP to feed real-time coding context (repositories, tickets, documentation) to AI copilots. AI dev platforms like Replit and Sourcegraph are working with MCP to enhance their AI features, allowing seamless retrieval of relevant code or data during generation. Notably, some enterprises have also begun implementing MCP: for example, fintech company Block (Square) and Apollo are early adopters that integrated MCP into their systems to connect internal data with AI assistants. Additionally, MCP’s momentum caught the attention of major tech players – Microsoft collaborated on a C# MCP SDK (released March 2025) to ensure .NET applications can easily use MCP, and OpenAI’s own Agents SDK added support for MCP servers, making OpenAI’s agents interoperable with the MCP tool ecosystem. This cross-vendor adoption (Anthropic, Google, Microsoft, OpenAI, etc.) within months of launch underscores MCP’s emergence as a de facto standard for tool integration. Overall, MCP’s adoption trend is developer-driven: it spread through open-source projects, developer blogs/tutorials, and quick integration into AI products, resulting in a fast-expanding user base in both open-source and commercial contexts.

Enterprise Partnerships and Support

Agent2Agent (A2A) Partners: From day one, A2A has been backed by an impressive roster of enterprise technology vendors and system integrators. Google announced contributions from “more than 50 technology partners” including Atlassian, Box, Cohere, Intuit, LangChain, MongoDB, PayPal, Salesforce, SAP, ServiceNow, UKG, Workday, and many others. These partners span SaaS application providers (Atlassian, Box, Workday), AI and data platform companies (Cohere for AI models, MongoDB for databases), financial tech (PayPal, Intuit), and enterprise software giants (Salesforce, SAP). Their involvement suggests that these companies intend to make their own agents or applications A2A-compatible. For example, a CRM agent from Salesforce or an IT helpdesk agent from ServiceNow could directly communicate with other agents in a client’s environment via A2A. In addition to software vendors, A2A is supported by leading consulting and IT services firms – e.g. Accenture, BCG, Capgemini, Deloitte, KPMG, McKinsey, PwC, Tata Consultancy Services (TCS), Infosys, Wipro, and others are on board. This indicates broad confidence in A2A among enterprise implementers; these firms likely plan to build solutions for clients using A2A (for instance, integrating agents across Oracle, SAP, and custom systems in a large enterprise). Such public commitments from multiple Fortune 500 companies and consultancies signal that A2A is seen as an industry-wide effort to enable AI interoperability. Many of these partners have issued supportive statements: partners praise A2A for “breaking silos” between enterprise apps and enabling scalable cross-platform AI workflows. This coalition gives A2A a strong foothold in enterprise settings – customers of those partners may soon find A2A options in their software. It’s also notable that Oracle and JetBrains appear among partner logos, even though not called out in text, further widening the enterprise net. In summary, A2A’s key partners are predominantly enterprise software providers and integrators, reflecting its strategy to gain adoption via enterprise channels and standard bodies (there is even a governance board for the protocol to manage contributions).

Model Context Protocol (MCP) Supporters: MCP’s partnerships are more informal and developer-centric, but several companies have stepped forward as early adopters or collaborators. Anthropic’s announcement highlighted Block, Inc. (the fintech company behind Square) and Apollo as early adopters integrating MCP to link their data stores with AI assistants. In Block’s case, the CTO endorsed MCP’s open approach to “connect AI to real-world applications” in a transparent, collaborative way. A number of developer tool companies are working with MCP: Zed (code editor), Replit (online dev environment), Codeium (AI code assistant), and Sourcegraph are using MCP to enhance AI capabilities in their platforms. For example, an IDE like Zed can use MCP to fetch relevant code snippets, GitHub issues or documentation for the AI assistant to reference, improving coding suggestions. These engagements show MCP gaining traction in the developer tools and AI startup ecosystem, where flexibility and integration with various data sources is paramount. We also see growing big-tech support: Microsoft has not officially “partnered” in a press-release sense, but the contribution of a C# MCP SDK by a Microsoft team and its release on NuGet is effectively an endorsement of MCP for enterprise .NET developers. Similarly, OpenAI’s inclusion of MCP compatibility in their Agents SDK means that OpenAI expects its users to leverage MCP connectors for tool use – a notable recognition of the standard. While MCP might not have a formal consortium like A2A, it has a community-driven partnership model: thousands of developers and companies contributing connectors, SDKs, and use-cases on GitHub. Anthropic is working with partners to create more pre-built MCP servers for popular enterprise systems (they released connectors for Google Drive, Slack, GitHub, GitLab, PostgreSQL, etc., often in collaboration with those platforms’ developers). In essence, MCP’s “enterprise partners” include any organization that builds or uses an MCP integration. So far this includes forward-leaning tech companies (fintech, coding tools) more so than legacy enterprise software vendors. However, the broad adoption (including by competitors in the AI space) implies industry-wide support. Even Google can be considered a supporter – Google’s ADK explicitly supports MCP alongside A2A , and Google Cloud’s documentation encourages using MCP to connect agents to data. This complementary stance shows that MCP’s openness has led to coopetition: multiple AI providers aligning on MCP as a shared standard for tools.

Community Feedback

Enthusiasm for Open Standards: Developers have generally responded positively to both MCP and A2A, as both address pain points in the AI agent workflow. MCP, having been out a bit longer, is often lauded in developer circles as a much-needed standard to avoid reinventing “plugin” integrations for every app. It’s been described as “a universal connector” that reduces fragmentation by letting any LLM agent access tools through a common interface. The analogy “like a USB-C port for AI” is frequently cited, resonating with developers who appreciate a single, standardized way to plug in any data source. This excitement is evident on GitHub – many developers started building MCP servers (connectors) for everything from web search to databases, leading to a rich ecosystem in a short time. Developers also value that MCP is model-agnostic and community-led. On social media and blogs, MCP is seen as “hacker-friendly” – it emerged from the AI community (driven by Anthropic and open-source contributors) and moved fast with frequent updates, which appeals to independent developers. For instance, the rapid release of SDKs in Python, TypeScript, Java, Kotlin, and C# within a few months impressed many, as it shows a responsive, multi-language community. This fast pace means developers can start experimenting and contributing immediately, which has fostered a sense of shared ownership.

A2A’s reception among developers has also been largely positive, especially for those working on multi-agent systems. Many were quick to call A2A the missing “interoperability language” for agents. The fact that it’s open-sourced and not tied to a single vendor’s framework reassures developers that they can adopt it without lock-in. Agent framework maintainers (like LangChain’s community) expressed interest in implementing A2A support so that agents built in those frameworks can talk to other agents. On forums, some have dubbed A2A and MCP “cousins” – MCP for tools, A2A for agent-to-agent – and are excited about using them together to build more complex agent ecosystems. The launch of A2A triggered substantial discussion on platforms like Hacker News and Reddit. Many developers are intrigued by the idea of agents negotiating tasks and UI formats via A2A’s constructs (the “Agent Card” and message parts were noted as novel features enabling dynamic discovery and rich interaction).

Skepticism and Cautions: Despite enthusiasm, developers have raised a few cautionary points. One common concern is the proliferation of standards – with MCP, A2A, and others (e.g. Cisco-led AGNTCY) all emerging around the same time, some developers worry about a “standards war” or fragmentation instead of convergence. There’s a bit of humorous cynicism comparing these agent protocols to past enterprise integration schemes. On Hacker News, for example, some likened A2A to “re-discovering SOA and WSDL, but for LLMs” – essentially cautioning that we’ve seen grand interoperability frameworks before (in web services) that became overly complex. However, others countered that modern AI agents can actually take advantage of dynamic discovery in ways past software couldn’t, so an open protocol might succeed where older approaches failed. Another point of discussion is security and trust. Developers acknowledge MCP and A2A are promising, but enterprise developers in particular have asked: how do we ensure a rogue agent or tool can’t misuse these powerful interoperability channels? The need for robust auth, auditing, and permissioning was frequently mentioned. Google’s emphasis on security and governance in A2A is likely a response to those concerns. Some open-source developers were initially skeptical of the heavy enterprise involvement in A2A (one HN commenter joked that seeing a long list of big corporate consultancies “made it seem worse” from a pure coder’s perspective). This highlights a cultural difference: MCP’s narrative (grassroots, open-source vibe) resonates strongly with indie developers, whereas A2A’s backing by enterprise firms brings credibility for corporate users but a slight wariness from independent devs. That said, many developers recognize the necessity of both protocols. The prevailing sentiment in the community is that standardization (even via multiple complementary standards) is better than ad-hoc solutions, and both MCP and A2A fill important gaps. Developers are already experimenting with combining them, reporting that using MCP connectors inside A2A task flows is feasible and powerful (for example, an agent can call an MCP tool mid-conversation with another agent). This hands-on exploration by the community will ultimately guide the best practices. In summary, developer sentiment sees MCP as an exciting, fast-moving toolset to play with immediately, and A2A as a welcome effort to bring order and interoperability to the growing zoo of agents – with some cautious optimism that these standards will mature without excessive complexity.

Strategic Perspectives and Developer Sentiment

In the AI community, influencers and analysts have debated the motivations and strategies behind these protocols. A particularly insightful commentary came from Sam Charrington (host of the TWIML AI podcast), who posted a widely-shared analysis on LinkedIn shortly after A2A’s release. He posited that “A2A is politically vs. technologically motivated” – meaning its creation was driven less by lack of technology (since MCP exists) and more by strategic concerns. Charrington pointed out that many big enterprise software companies involved in A2A (e.g. Salesforce, SAP, Oracle, Workday) “don’t want to be anybody’s ‘tool’” in an MCP-dominated ecosystem. In other words, if everyone used MCP alone, then an AI orchestrator (perhaps Anthropics’ Claude or OpenAI’s systems) could directly tap into these companies’ data and workflows as tools, potentially reducing those companies’ control or differentiation. By backing A2A, those firms ensure a paradigm where each can have its own agent that collaborates on equal footing, rather than just being a back-end plugin. This perspective casts A2A as an enterprise defense play – a way to keep agency and control in the hands of established platform players in the age of AI. Charrington does acknowledge that “MCP has strong momentum among individual developers” – it’s beloved by the fast-moving dev crowd – but notes that enterprises have “open security, supply chain and governance issues” with it. A2A, tied into enterprise platforms, could address these by offering more structured permissions, audit logs, and alignment with enterprise IT policies. His closing question encapsulated the landscape: will the future favor “a fast-moving standard beloved by devs, or a higher-level flexible protocol backed by enterprise giants?". Many in the community suspect that both will coexist in their respective domains of strength, and indeed likely work together (as they are designed to).

Other commentary has reinforced this dichotomy. A Medium article by NoAI Labs in April 2025 described MCP as “developer-led” and focused on reducing integration fragmentation, versus A2A as “enterprise-driven” aiming at cross-platform workflow automation. Thought leaders have pointed out that Google’s close partnership with Anthropic (recall that Google is a major investor in Anthropic) may be why the two protocols were made to complement each other rather than compete directly – a strategic alignment to cover both bases. There is also reporting on how these standards factor into the AI strategy of the companies: Google, by championing A2A, strengthens its appeal to businesses that want multi-agent systems with tight governance. Anthropic, by open-sourcing MCP, increases its influence among developers and ensures that its Claude AI can easily integrate into many tools and workflows (undercutting the proprietary plugin ecosystems of rivals).

Recent tech conference talks and webinars frequently feature A2A/MCP discussions. At Google Cloud Next ‘25, demos showed an HR hiring scenario where multiple A2A agents (sourcing, interviewing, scheduling) worked together – something not feasible without a protocol like A2A. Meanwhile, Anthropic’s team has been showing how MCP lets an AI agent maintain context across different tools, e.g. writing code in an IDE while pulling data via MCP from a database and a documentation wiki – highlighting productivity gains from the standard.

Overall, the commentary suggests a consensus that standards for AI agent intercommunication and tool-use are timely and necessary. MCP and A2A are often cited together as complementary pillars of an emerging “AI agent stack.” Strategically, MCP’s rapid adoption forced larger players to respond (Google chose to endorse and augment it via A2A rather than fight it, while others like Cisco are proposing alternatives). Politically, it reflects a tug-of-war between open, community-driven innovation and enterprise desire for control and risk mitigation. Yet, the prevailing narrative as of April 2025 is optimistic: by addressing different layers (tool context vs. agent orchestration) and catering to different audiences (developers vs. enterprises), MCP and A2A might both thrive and even reinforce each other, rather than one winning at the expense of the other.

MCP vs A2A: Fast-Moving Standard vs. Enterprise Solution

To crystallize the differences in strategy: Anthropic’s MCP has emerged as a developer-led, fast-evolving standard. It was released openly and iteratively, quickly attracting a community that implemented it in various languages and integrated countless tools. This bottom-up adoption means MCP became popular among startups, indie developers, and even other AI labs as a de facto standard for tool integration. Its strength is agility and widespread grassroots support, which drives innovation at a breakneck pace – but it also faces challenges in formal governance and enterprise trust, as issues like security policies are still being refined in the open forum. Google’s A2A, in contrast, represents an enterprise-backed, risk-aware approach. It was developed in consultation with dozens of big companies to ensure it meets corporate requirements for security, compliance, and reliability. A2A moves more deliberately – it launched with a draft spec and a promise of a production-ready version later in 2025, indicating a careful, stability-focused rollout. Its governance is structured (with Google and partners overseeing the standard) to instill confidence for enterprise adoption. This means enterprises are more likely to implement A2A for mission-critical workflows where “trustability” and support are key. The flip side is that A2A’s evolution may be slower and more measured, and it enters slightly later in the game, seeded by top-down influence rather than organic spread.

In practical terms, MCP’s fast pace has already produced a rich ecosystem of integrations and has mindshare among developers building the next generation of AI apps. A2A’s methodical, partnership-driven strategy aims to make it the standard in boardrooms – the protocol that CIOs will be comfortable using to connect AI agents across their enterprise software portfolio (especially those from vendors who back A2A). It is telling that one is often characterized as the “cool hacker kid” and the other as the “enterprise suit” in community discussions. As one observer succinctly put it: “MCP is the cool hacker kid, A2A is the enterprise suit. One moves fast, the other gets boardroom approval.” Both have the potential to shape how AI systems interoperate. The likely outcome, as recent commentary suggests, is a dual ecosystem: MCP continuing to drive rapid innovation and being embraced in developer-heavy contexts, and A2A providing a unifying, governance-friendly layer adopted by enterprises – with interoperability between the two ensuring users get the best of both worlds.

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