Validates the end-user provided user_code from the user-interaction of the Device Authorization Grant. If you build your own activation form you should validate the user provided code prior to beginning the Authorization grant. OR Validates the end-user provided user_code from the user-interactio...
Part of the Fusionauth server.
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AI agents call retrieveDeviceValidate to retrieve information from Fusionauth without modifying any data. This is common in research, monitoring, and reporting workflows where the agent needs context before taking action. Because read operations don't change state, they are generally safe to allow without restrictions -- but you may still want rate limits to control API costs.
Even though retrieveDeviceValidate only reads data, uncontrolled read access can leak sensitive information or rack up API costs. An agent caught in a retry loop could make thousands of calls per minute. A rate limit gives you a safety net without blocking legitimate use.
Read-only tools are safe to allow by default. No rate limit needed unless you want to control costs.
{
"version": "1",
"default": "deny",
"tools": {
"retrieveDeviceValidate": {}
}
}See the full Fusionauth policy for all 314 tools.
These attack patterns abuse exactly the kind of access retrieveDeviceValidate gives an agent. Each links to the full case and the policy that stops it:
Other read tools across the catalogue. The same approach applies to each: allow, with a rate cap to control cost.
Validates the end-user provided user_code from the user-interaction of the Device Authorization Grant. If you build your own activation form you should validate the user provided code prior to beginning the Authorization grant. OR Validates the end-user provided user_code from the user-interaction of the Device Authorization Grant. If you build your own activation form you should validate the user provided code prior to beginning the Authorization grant.. It is categorised as a Read tool in the Fusionauth MCP Server, which means it retrieves data without modifying state.
Register the Fusionauth MCP server in PolicyLayer and add a rule for retrieveDeviceValidate: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Fusionauth. Nothing to install.
retrieveDeviceValidate is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the retrieveDeviceValidate rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for retrieveDeviceValidate. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
retrieveDeviceValidate is provided by the Fusionauth MCP server (@fusionauth/mcp-api). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 314 Fusionauth tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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