Secure FastMCP with Cerbos authorization
Control what AI agents and tools can access with policy-driven authorization powered by Cerbos.
MCP authorization
Control access to MCP tools and resources with fine-grained Cerbos policies
cerbos-fastmcp middleware
Drop-in middleware that enforces authorization on every tool call and resource access
Policy as code
Define who can use which AI tools using human-readable YAML policies
How Cerbos works with FastMCP
AI agents and tools introduce a new class of authorization challenges. They act on behalf of users, access sensitive data, and chain operations, all of which need fine-grained access control.
Cerbos provides policy-driven authorization that controls what AI systems can do, which data they can access, and on whose behalf. Policies are written in human-readable YAML and evaluated at request time.
With Cerbos and FastMCP, you get guardrails that scale with your AI adoption, centrally managed policies, full audit trails, and sub-millisecond decision times that don't slow down agent workflows.
How Cerbos secures FastMCP agents
- Define policies for AI agent actions and data access, Write YAML policies that specify which tools, data, and operations each agent or user can access.
- Agent requests authorization from Cerbos, Before performing an action, the AI agent sends the user context, tool, and target resource to the PDP.
- Cerbos evaluates context, tool, and resource, The PDP applies fine-grained policies considering the user's identity, the requested tool, and the target data.
- Agent proceeds or is denied, Cerbos returns an allow or deny decision and the agent framework enforces it, with a full audit trail.
FAQ
How does Cerbos secure FastMCP agents?
Cerbos evaluates fine-grained policies at every tool call and data access, ensuring AI agents only perform actions and access data they are authorized for, on behalf of the requesting user.
Can I audit what my AI agents are doing?
Yes. Every authorization decision is logged with full context, the principal, resource, action, and result. This gives you a complete audit trail of AI agent behavior.
Learn more about Cerbos
Related integrations
View all integrations →
Cerbos + FastMCP
- Cerbos policies govern AI agent tool access and data visibility
- Full audit trail for every AI tool call and data access
- Per-user permissions enforced across autonomous agent workflows
- Sub-millisecond policy evaluation with no agent pipeline overhead
Authorization for AI systems
By industry
By business requirement
Useful links
What is Cerbos?
Cerbos is an end-to-end enterprise authorization software for Zero Trust environments and AI-powered systems. It enforces fine-grained, contextual, and continuous authorization across apps, APIs, AI agents, MCP servers, services, and workloads.
Cerbos consists of an open-source Policy Decision Point, Enforcement Point integrations, and a centrally managed Policy Administration Plane (Cerbos Hub) that coordinates unified policy-based authorization across your architecture. Enforce least privilege & maintain full visibility into access decisions with Cerbos authorization.