retrieveDeviceUserCode
Retrieve a user_code that is part of an in-progress Device Authorization Grant. This API is useful if you want to build your own login workflow to complete a device grant. This request will require an API key. OR Retrieve a user_code that is part of an in-progress Device Authorization Grant. This...
This record as markdown: /tools/io-fusionauth-mcp-api/retrievedeviceusercode.md
What retrieveDeviceUserCode does on Fusionauth
AI agents call retrieveDeviceUserCode to retrieve information from Fusionauth without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Why retrieveDeviceUserCode is rated Low
This tool queries and returns data (a user_code) without creating, modifying, deleting, or executing operations. It is a read-only retrieval operation with minimal security risk—disclosure of a device code in progress has limited impact since device authorization flows are typically time-bound and require additional authentication.
From the tool's definition Tool name contains 'retrieve' and description states 'Retrieve a user_code that is part of an in-progress Device Authorization Grant.' The action is purely informational—fetching an existing code for an OAuth device flow without modification or execution.
Attacks that exploit this kind of access
The rule that runs retrieveDeviceUserCode safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Fusionauth, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For retrieveDeviceUserCode, this is the rule to start with:
retrieveDeviceUserCode is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect Fusionauth, apply this rule, and every retrieveDeviceUserCode call is checked against it from then on.
Questions about retrieveDeviceUserCode
Retrieve a user_code that is part of an in-progress Device Authorization Grant. This API is useful if you want to build your own login workflow to complete a device grant. This request will require an API key. OR Retrieve a user_code that is part of an in-progress Device Authorization Grant. This API is useful if you want to build your own login workflow to complete a device 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 retrieveDeviceUserCode: 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.
retrieveDeviceUserCode 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 retrieveDeviceUserCode 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 retrieveDeviceUserCode. 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.
retrieveDeviceUserCode 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.
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