Microsoft Warns Poisoned MCP Tool Descriptions Can Make AI Agents Leak Data

New Microsoft research shows how attackers can hijack AI agents that act on a user's behalf, using nothing more than a poisoned tool description to make the agent quietly hand over company data to an outsider.

The trick is that the agent never breaks a rule. Every step looks routine, so in a default setup no alarm may fire.

The work comes from Microsoft Incident Response and its