The atmosphere at Microsoft’s Build developer conference this year was charged with anticipation and concern in equal measure, as the company made public its ambitious plans to embed the Model Context Protocol (MCP) deep within the fabric of Windows itself. The native inclusion of MCP marks a radical step towards what Microsoft is branding an ‘agentic OS’—a Windows environment where AI agents, coordinated workflows, and automated app-to-app communication become integral to the user experience. However, as much as MCP promises to redefine productivity and automation on Windows, its introduction also surfaces complex and arguably unprecedented security questions that are already drawing sharp scrutiny from both developers and IT security experts.
The MCP was conceptualized only half a year ago by Anthropic, with its first iteration aiming to provide a universal, AI-friendly protocol for accessing data across diverse systems. Built on JSON-RPC 2.0, MCP’s rapid adoption and evolution have been as marked as its growing scope. It’s no longer just a means to fetch or manipulate data; it’s a flexible protocol for generalized automation, letting MCP servers—running locally or on remote hosts—announce their capabilities and accept granular commands from clients.
Microsoft’s decision to make MCP part of core Windows infrastructure reflects a vision of seamless automation. Consider a typical scenario: A user could issue a single prompt, such as, “Prepare a performance summary from my team’s tracked hours, chart the results in Excel, and email it to HR.” Under the hood, an AI agent would leverage MCP to invoke system- and app-level functions: extracting the necessary data, running calculations, triggering Excel to generate the spreadsheet, and launching the email—all stitched together by a protocol that standardizes these actions across both native and third-party tools.
This shift primes Windows for a new era—where “agentic OS” refers to operating systems that not only host applications but can serve as orchestrators for complex, distributed flows of work. The user (or their AI-powered digital assistant) need not care which application or service executes each fragment of a workflow, nor where it physically runs, as long as the desired outcome is delivered securely and efficiently.
Strengthening authentication, ensuring continuous security reviews (particularly for third-party and open-source MCP servers), and rigorous policy enforcement will be ongoing battles.
How comprehensively will users be able to see, control, and revoke what agents and MCP servers are doing on their behalf? Microsoft’s answer—central audit and consent in the MCP proxy—sounds promising, but actual granularity and transparency will be critical.
MCP, in its design, attempts to avoid the pitfalls of binary interfaces—avoiding the memory and class registration issues that plagued COM—by building on widely adopted, text-based web technologies (e.g., JSON-RPC 2.0) and modern security expectations. Whether this will be enough, especially as the attack landscape becomes more AI-driven, remains an open question.
But profound power carries profound responsibility. MCP, as currently envisioned and implemented, should be seen as “potentially transformative but not yet fully proven.” The technical foundations are sound—the use of registries, per-action privilege declarations, and standardized interfaces all align with best practices. Partnerships with Anthropic, GitHub, and other leaders signal industry alignment. Yet real-world rollout—especially at enterprise scale, with exposure to sophisticated adversaries and legacy system dependencies—will demand patience, vigilance, and a willingness to rapidly iterate in response to emerging threats.
In the final analysis, Microsoft’s willingness to foreground security concerns from the outset is commendable and, frankly, necessary, given Windows’ historic and ongoing role as a target-rich environment for attackers. Whether developers, IT leaders, and users can balance the extraordinary promise of an agentic OS against the very real challenges of securing its foundation will define not only the success of MCP, but the next chapter in the Windows story. For now, the Build conference has set the direction; the journey—and the debate—has only just begun.
Source: devclass MCP will be built into Windows to make an 'agentic OS' but security will be a key concern • DEVCLASS
The Evolution and Architecture of MCP in Windows
The MCP was conceptualized only half a year ago by Anthropic, with its first iteration aiming to provide a universal, AI-friendly protocol for accessing data across diverse systems. Built on JSON-RPC 2.0, MCP’s rapid adoption and evolution have been as marked as its growing scope. It’s no longer just a means to fetch or manipulate data; it’s a flexible protocol for generalized automation, letting MCP servers—running locally or on remote hosts—announce their capabilities and accept granular commands from clients.Microsoft’s decision to make MCP part of core Windows infrastructure reflects a vision of seamless automation. Consider a typical scenario: A user could issue a single prompt, such as, “Prepare a performance summary from my team’s tracked hours, chart the results in Excel, and email it to HR.” Under the hood, an AI agent would leverage MCP to invoke system- and app-level functions: extracting the necessary data, running calculations, triggering Excel to generate the spreadsheet, and launching the email—all stitched together by a protocol that standardizes these actions across both native and third-party tools.
MCP’s Key Components on Windows
Microsoft’s buildout of MCP within Windows centers on several foundational features:- Local MCP Registry: Windows will host a dedicated registry that catalogs all available MCP servers, supporting rapid discovery whether these are core OS modules or third-party offerings.
- Built-in MCP Servers: The first wave will include servers that expose core system functions—such as file-system access, window management, and integration with the Windows Subsystem for Linux—making these services available for automation by AI agents.
- App Actions API: This new API empowers third-party developers to define and expose discrete actions (like “create task,” “send message,” “generate report”) as accessible endpoints. These can be called via MCP, greatly expanding the horizon for cross-app automation and AI-driven workflows.
- Ecosystem Partnerships: At launch, companies like Anthropic, Figma, and Perplexity are integrating MCP into their Windows apps. Third-party developers including Zoom, Todoist, and Spark Mail are also implementing App Actions, signaling early traction across productivity tooling.
Why the Shift to Agentic Operating Systems Matters
Windows is no stranger to automation. Technologies like the Component Object Model (COM) and its derivatives (notably OLE Automation and ActiveX) have, for decades, enabled inter-app communication and programmable controls. What distinguishes MCP is both its higher level of abstraction and its deeply modern orientation: It’s JSON-native rather than binary, designed for distributed and local AI agents, and fundamentally oriented around structured, service-like commands rather than exposure of granular object models.This shift primes Windows for a new era—where “agentic OS” refers to operating systems that not only host applications but can serve as orchestrators for complex, distributed flows of work. The user (or their AI-powered digital assistant) need not care which application or service executes each fragment of a workflow, nor where it physically runs, as long as the desired outcome is delivered securely and efficiently.
Productivity Boon: Automation for All
For individuals and organizations, these capabilities hold immediate promise:- Seamless Automation: Chaining together functionality across apps—Excel report generation, email dispatch, file categorization—becomes trivial with natural language or agentic prompts.
- Reduce Friction: Third-party apps can opt-in to expose standardized “actions,” dramatically reducing the need for brittle workarounds, scripting, or bespoke integration middleware.
- Extendibility: Enterprises and independent developers alike can register their own MCP servers, extending the automation surface beyond Microsoft’s ecosystem.
Security: The Crucial Battleground
With all this promise, Microsoft is also quick to admit that MCP’s power could easily translate into new vectors of attack—and history provides abundant cautionary tales. COM, for example, has been the backbone for automation on Windows for years but it’s also left a legacy of security headaches, from notorious exploits in ActiveX controls within Internet Explorer to OLE’s entanglement in Office macro malware. MCP risks amplifying these dangers if left unchecked, according to senior Microsoft security architect David Weston, who outlined seven attack vectors at Build:- Cross-Prompt Injection: Where malicious input in one context can override or subvert the intended instructions of an agent in another, leading to compromises or data leakage.
- Authentication Gaps: MCP’s current authentication protocols are inconsistent and underdeveloped, opening doors for unauthorized command execution.
- Credential Leakage: Sensitive information could inadvertently be exposed via poorly designed actions or insufficient access controls.
- Tool Poisoning: The use of unverified or malicious MCP servers could turn legitimate automation into an attacker’s toolkit.
- Lack of Containment: Without strong policy-based isolation, an errant or malicious MCP server could overreach its intended privileges.
- Limited Security Review: Many MCP servers may not undergo routine or deep security vetting—a risk, given the protocol’s system-level access.
- Supply Chain Threats: As the pool of third-party (and even rogue) MCP servers grows, the risk of compromise through the software supply chain rises.
Microsoft’s Security Roadmap for MCP
Mindful of these pitfalls, Microsoft is drawing from previous missteps (notably in the COM and ActiveX eras) and promising a raft of protective measures. Several key controls are being previewed or committed to:- Centralized Proxy for MCP Interactions: All traffic between MCP clients and servers will pass through a system-level proxy. This provides a single point for policy enforcement, consent management, operation auditing, and real-time inspection by security software.
- Baseline Security Requirements for MCP Registry Inclusion: MCP servers must be signed, undergo security interface testing, and publicly declare their required privileges to be allowed into the local registry—raising the bar for both developers and software vendors.
- Runtime Isolation: Tighter runtime boundaries and granular permissioning (akin to app sandboxing on mobile OSes) will aim to contain any damage from compromised or buggy servers.
- Expanded Security Partnerships and Governance: Microsoft is partnering with GitHub and others on the official MCP steering committee, working on both an improved authorization specification and a future public registry service that aims for transparency and trustworthiness in the ecosystem.
Strengths and Strategic Advantages of Windows MCP
The drive to build MCP into Windows speaks to Microsoft’s long-term goal of making Windows not just a platform for running software but a hub for intelligent, automated, and personalized workflows spanning apps, clouds, and devices. Key strengths in this vision include:Cross-Platform and Third-Party Reach
By designing MCP as a protocol that is equally at home on Windows, in the cloud, and inside third-party apps (even web-based ones, thanks to NLWeb), Microsoft moves away from the historic walled gardens of Windows automation. Instead, it positions itself at the center of a new, federated automation universe, competing with and integrating into rival ecosystems (e.g., Google or Apple environments).AI-Empowered Workflows
AI agents are most effective when they can interface with real-world tools and data. By formalizing and standardizing the bridge between LLM-based agents and application capabilities, MCP unlocks previously labor-intensive automation for non-programmers. Users can ultimately describe “what” they want (in natural language or via structured intent), and agents can determine “how” to achieve it securely and efficiently.Transparency and Governance
The formalization of MCP registries (both local and a planned public instance), baseline security vetting, and explicit privilege declarations align with best practices for trust and transparency. While these measures are only as robust as their implementation, their inclusion at the architecture stage sets a strong precedent.Challenges, Risks, and Open Questions
For all the strengths and grand ambitions behind MCP in Windows, several significant risks and unresolved questions warrant close attention.Security Maturity and Real-World Complexity
At launch, significant portions of the promised security apparatus for MCP will be missing or immature. As with any new system-level protocol, attackers and security researchers will have a period of head start to scrutinize and potentially exploit overlooked edge cases. The parallel with COM and its security legacy is unavoidable; despite best efforts, binary protocols and automation APIs have repeatedly become attack surfaces for malware, data leakage, and privilege escalation.Strengthening authentication, ensuring continuous security reviews (particularly for third-party and open-source MCP servers), and rigorous policy enforcement will be ongoing battles.
Supply Chain and Ecosystem Risks
As the MCP ecosystem grows, the threats from rogue or vulnerable components multiply. Just as rogue NPM, PyPI, or Docker packages have become sources of software supply chain infiltration, malicious or compromised MCP servers present a new attack vector. Microsoft’s proposed registry policies, mandatory signing, and privilege declarations are meaningful—but only if they are universally enforced and routinely audited.Consent, Privacy, and User Control
The automation of emails, reports, data exports, and more can blur the boundary between user intent and agent behavior. Explicit user consent and transparent audit trails will be essential, not only for technical safety but also for regulatory compliance (e.g., GDPR, CCPA).How comprehensively will users be able to see, control, and revoke what agents and MCP servers are doing on their behalf? Microsoft’s answer—central audit and consent in the MCP proxy—sounds promising, but actual granularity and transparency will be critical.
Interoperability and Fragmentation
By its nature, MCP aims for horizontality—cross-platform automation, broad third-party buy-in, and open registries. The risk is fragmentation if competing ecosystems (e.g., other OS vendors, cloud providers) diverge on security, features, or authentication measures. The presence of a steering committee, open specs, and early cloud partnerships mitigate this, but market realities may see de facto “forks” or competing protocols emerging.Backward Compatibility and Legacy Systems
Large enterprises with mission-critical legacy Windows applications will need a clear migration path. The relationship between MCP-based automation and existing systems built on COM, PowerShell, Windows Services, or other legacy foundations remains to be seen. Transitional tools, shims, or phased sunset plans could be required to avoid disruption or abandonment of long-functioning workflows.Comparisons to Historical Windows Automation Technologies
The strong parallels between MCP and the decades-old COM/OLE/ActiveX stack are both instructive and cautionary. In the heyday of Windows automation, these technologies enabled robust document embedding, inter-app scripting, and extensibility—but at great security cost. ActiveX, in particular, became a byword for browser exploits and untrusted code execution, eventually leading to browser vendors phasing it out entirely.MCP, in its design, attempts to avoid the pitfalls of binary interfaces—avoiding the memory and class registration issues that plagued COM—by building on widely adopted, text-based web technologies (e.g., JSON-RPC 2.0) and modern security expectations. Whether this will be enough, especially as the attack landscape becomes more AI-driven, remains an open question.
The Road Ahead: Promise and Caveat
Windows’ evolution into an ‘agentic OS’ is, given current trends in AI, automation, and digital workflow, an almost inevitable next step for Microsoft and the broader industry. The combination of standardized protocol-driven automation, AI assistant integration, and a vibrant third-party action ecosystem could transform how software is used and interlinked on the world’s most widely deployed desktop platform.But profound power carries profound responsibility. MCP, as currently envisioned and implemented, should be seen as “potentially transformative but not yet fully proven.” The technical foundations are sound—the use of registries, per-action privilege declarations, and standardized interfaces all align with best practices. Partnerships with Anthropic, GitHub, and other leaders signal industry alignment. Yet real-world rollout—especially at enterprise scale, with exposure to sophisticated adversaries and legacy system dependencies—will demand patience, vigilance, and a willingness to rapidly iterate in response to emerging threats.
In the final analysis, Microsoft’s willingness to foreground security concerns from the outset is commendable and, frankly, necessary, given Windows’ historic and ongoing role as a target-rich environment for attackers. Whether developers, IT leaders, and users can balance the extraordinary promise of an agentic OS against the very real challenges of securing its foundation will define not only the success of MCP, but the next chapter in the Windows story. For now, the Build conference has set the direction; the journey—and the debate—has only just begun.
Source: devclass MCP will be built into Windows to make an 'agentic OS' but security will be a key concern • DEVCLASS
