Dynamic Conditions: Bringing Runtime ABAC Expressions to OpenFGA
MCP agents are becoming capable of calling an increasingly broad range of tools. That creates a corresponding authorization challenge. It is not enough to know whether an agent can call a tool. In many cases, authorization also depends on the request's runtime context.
For example, an agent might be allowed to send Slack messages, but only to the #product-announcements channel.
OpenFGA is well-suited to model relationships between users, groups, roles, agents, tools, and resources. MCP gateways can use those relationships as an enforcement point for deciding which agents are allowed to invoke which tools.
However, highly dynamic policies can be difficult to represent using a traditional OpenFGA model. If every possible runtime constraint requires a schema change, authorization logic becomes harder to maintain, especially when MCP servers and their tools change frequently.
Today, we are introducing Dynamic Conditions, an experimental OpenFGA feature that lets you attach CEL expressions directly to authorization tuples and evaluate them at runtime.
