importUsersWithId
Bulk imports users. This request performs minimal validation and runs batch inserts of users with the expectation that each user does not yet exist and each registration corresponds to an existing FusionAuth Application. This is done to increases the insert performance. Therefore, if you encounte...
This record as markdown: /tools/io-fusionauth-mcp-api/importuserswithid.md
What importUsersWithId does on Fusionauth
AI agents use importUsersWithId to create or update resources in Fusionauth, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Fusionauth environment.
Why importUsersWithId is rated Medium
This tool creates new user records in bulk within FusionAuth. While the operation is reversible (users can be deleted), it modifies the system state significantly by inserting potentially many user accounts.
From the tool's definition Tool description states 'Bulk imports users' and 'batch inserts of users', indicating creation of multiple user records in the system.
Attacks that exploit this kind of access
The rule that runs importUsersWithId 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 importUsersWithId, this is the rule to start with:
importUsersWithId stays usable, but capped: an agent stuck in a loop can't make hundreds of changes a minute. 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 importUsersWithId call is checked against it from then on.
Questions about importUsersWithId
Bulk imports users. This request performs minimal validation and runs batch inserts of users with the expectation that each user does not yet exist and each registration corresponds to an existing FusionAuth Application. This is done to increases the insert performance. Therefore, if you encounter an error due to a database key violation, the response will likely offer a generic explanation. If you encounter an error, you may optionally enable additional validation to receive a JSON response body with specific validation errors. This will slow the request down but will allow you to identify the cause of the failure. See the validateDbConstraints request parameter. It is categorised as a Write tool in the Fusionauth MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Fusionauth MCP server in PolicyLayer and add a rule for importUsersWithId: 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.
importUsersWithId is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the importUsersWithId 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 importUsersWithId. 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.
importUsersWithId 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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