What each vendor actually announced
Palo Alto: Cortex XDR 6.0 and Cortex XDR One. Palo Alto's blog says Cortex XDR One puts XDR and Agentic Endpoint Security (AES) in a single console and sensor. It says the product discovers agents, MCP servers, plugins, models and extensions and scores the risk each one introduces. The same post lists:
- Native application control, which inventories executed binaries on Windows and Mac endpoints and lets admins write allow or block policies at publisher, application or file level.
- Runtime protection that records agent actions in a session-based audit trail and intercepts policy-violating actions before they run.
- A Cortex Targeted Sensor that deploys only selected modules, such as AES or Active Directory security posture management, alongside an existing third-party EDR. It has a one-step path to the full Enterprise XDR Sensor.
- Behavioral threat protection plus small language models on the endpoint, aimed at zero-days, living-off-the-land attacks and obfuscated scripts. New protections arrive through content updates with no agent upgrade.
All of this is vendor-reported. I found no independent lab results specific to 6.0.
The Claude Cowork caveat. On November 2, Palo Alto announced a Cortex XDR integration with Claude Cowork. Cowork runs agent tasks inside a small local virtual machine that works as a security boundary. That isolation also stops the EDR agent from seeing what the agent does. Palo Alto says a lightweight sensor inside the VM will track accessed systems, file changes and executed commands. The integration is not available yet. Palo Alto says private preview begins "in the coming months". Its forward-looking-statements notice says unreleased features may not arrive when expected or at all. Don't count this toward a purchase decision today.
Microsoft: ISOC in Defender. Microsoft Learn describes ISOC as bringing XDR and SIEM capabilities, threat intelligence, automation and AI into the Defender portal. It is explicitly a preview, and capabilities and availability may change. The eligibility rules matter:
- During this phase, ISOC is open to eligible customers with Defender Suite, Microsoft 365 E5 or Microsoft 365 E7 who do not have an active Microsoft Sentinel workspace.
- Microsoft tells Sentinel users to keep their existing experience and not to disconnect a production workspace just to qualify.
- Case management, natural-language playbook generation, automation rules and workbooks work without an ISOC workspace.
- UEBA, Content hub, CI/CD, threat intelligence and Azure and third-party data ingestion need a workspace, and therefore an Azure subscription.
- Eligible customers get 30 days of included Defender data retention in this phase. Microsoft says more than 500 connectors are available, and extra ingestion charges may apply.
Sophos: Fusion and the Taegis rebuild. Sophos calls Fusion the evolution of Sophos Central, rebuilt on an architecture that incorporates Secureworks Taegis analytics after the 2025 acquisition. Its July press release says the rebuilt XDR adds thousands of detectors, a new analyst experience and built-in SOAR playbooks. It gave August 15, 2026 as the general availability date. It also says Sophos AI Defense had early access in August and general availability in October 2026. The release cites more than 500 third-party integrations.
Microsoft's AI-agent discovery: GA, with qualifiers
Microsoft's local AI agent discovery needs more care than a headline suggests.
- A Microsoft Tech Community post says discovery of agents and their configured MCP servers on Windows and macOS is generally available. It cites coverage of more than 50 supported agents and MCP servers.
- The same post says runtime protection for local agents on Windows is still in preview. Both capabilities will be available to Defender for Endpoint P2 and higher customers.
- The date is unclear. The Learn page was updated November 3. One outside write-up, from Exchange Anywhere, dates Microsoft's announcement to October 29. It also notes that an earlier Learn page still labelled macOS discovery as preview. Check the current support matrix for your platform.
- Discovery is observation-based. Defender identifies a process-based agent when it sees the process running. An inventory entry is not proof of active use, and the feature is not a complete software inventory.
- MCP server configuration discovery still needs antivirus active mode and real-time protection.
- Exchange Anywhere says discovery needs Microsoft's commercial cloud and that sovereign and national clouds are not supported. That is a secondary source, so confirm it against current Microsoft documentation if you are a government customer.
Comparison on what can be relied on
| Area | Cortex XDR 6.0 | Microsoft Defender | Sophos |
|---|---|---|---|
| Agent discovery | Announced as part of 6.0; broadest stated list (agents, MCP servers, plugins, models, extensions) | GA on Windows and macOS for supported agents on onboarded devices | AI Defense for shadow AI visibility, GA October 2026 per Sophos |
| Runtime control | Listed in 6.0 | Preview (Windows) | Policy-focused per Sophos's description |
| Mixed-EDR deployment | Targeted Sensor beside third-party EDR | Pulls toward Microsoft's own endpoint stack | Open integrations, with native control points |
| SIEM layer | Not part of the 6.0 announcement | ISOC preview, E5/E7/Defender Suite without Sentinel | Next-Gen SIEM, GA August 15, 2026 |
| Independent testing of agent features | None found | None found | None found |
What to treat with caution
The source article also contains marketplace price quotes, analyst awards, customer-growth figures and a "who wins" scorecard. I could not tie those figures to primary sources in this research. I have left them out. The Microsoft per-GB ingestion rate, the Defender Suite and Defender for Business prices, and the Sophos per-user prices should each be confirmed with your reseller or Microsoft's own pricing pages before they go into a budget.
One structural point holds regardless of the numbers. Palo Alto's newest controls are the most ambitious on paper but the least proven in public. Microsoft's discovery is shipped, but its richer runtime and disruption features are preview-stage. Sophos has the clearest platform story, but its agent controls are the least detailed in the material I reviewed.
How to evaluate them for your estate
- Check your license position first. For Microsoft, discovery needs Defender for Endpoint Plan 2 or higher, and ISOC needs Defender Suite, E5 or E7.
- Confirm Sentinel status. If you already run a Sentinel workspace, ISOC is not meant to replace it during the preview.
- Define your agent list. Pick the coding or desktop agents your developers actually use, and note the MCP servers they are configured with.
- Run a pilot on a small set of endpoints. See whether each console shows the agent, its MCP configuration, the device and the account. Remember that Defender only lists agents it has observed running.
- Test coexistence. If you keep an incumbent EDR, Palo Alto's targeted sensor is designed for that case. Test it for conflicts before widening the rollout.
- Get claims in writing. Ask each vendor to state which agent features are GA and which are preview, and on which operating systems.
Bottom line
For Microsoft 365 E5 shops, Defender offers the fastest route to shipped agent discovery. Its limits are the preview status of runtime protection and ISOC, and the need to confirm the Defender for Endpoint P2 license. Cortex XDR 6.0 is worth piloting if you must keep a third-party EDR and want agent governance now. Sophos Fusion fits teams that want a platform and managed operations from one vendor. Until labs or your own pilot test the agent controls, every claim about stopping an agent mid-command is still a vendor claim.