The PlainID Integration for Kong Gateway lets you enforce PlainID Policies on both MCP tool calls and REST API responses from a single plugin, without changing your upstream services.
The Plugin makes two kinds of authorization decisions:
- Permit or deny: for each request, PlainID's Policy Decision Point (PDP) decides whether the call is allowed. Kong Gateway blocks denied calls before they reach the upstream server or API.
- Masking: for calls that are permitted, PlainID's JSON Filtering Authorizer can mask or remove specific fields in the response, based on the calling identity. The response structure stays the same. Only the field values change.
For MCP servers, the Plugin filters which tools each identity can see and use, so an Agent sees only the tools its Policies allow. For REST APIs, the Plugin authorizes each call and can mask sensitive fields in the response before Kong Gateway returns it to the caller.
Both decisions draw on the same Policies you already manage in PlainID. PlainID evaluates each request in real time, so a Policy change takes effect on the next call. No redeploy or code change required.
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See Configuring Kong for installation and configuration steps.