add_visitor · API-Central MCP: Risk & Policy

WHAT IT DOES

What add_visitor does on API-Central

AI agents use add_visitor to create or update resources in API-Central — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your API-Central environment.

WHY IT NEEDS A POLICY

Why add_visitor needs a policy

This tool creates new visitor/user accounts in the network access control system, which is a Write operation—data is created and can be modified or deleted. Severity is medium because compromised account creation could enable unauthorized network access, but the blast radius is somewhat contained by the visitor account nature and expiration settings.

From the tool's definition Create a Central NAC visitor account. The tool generates new user accounts with parameters for username (name=login username) and expiration time (expire_at ISO 8601), which are reversible creations of authentication credentials.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

add_visitor Rate-limited

add_visitor 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.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "add_visitor": {
      "limits": [
        {
          "counter": "add_visitor_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches API-Central, so you can run agents against it safely.

FAQ

Questions about add_visitor

What does the add_visitor tool do? +

Create a Central NAC visitor account. name=login username; expire_at ISO 8601. It is categorised as a Write tool in the API-Central MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on add_visitor? +

Register the API-Central MCP server in PolicyLayer and add a rule for add_visitor: 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 API-Central. Nothing to install.

What risk level is add_visitor? +

add_visitor is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit add_visitor? +

Yes. Add a rate_limit block to the add_visitor 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.

How do I block add_visitor completely? +

Set action: deny in the PolicyLayer policy for add_visitor. 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.

What MCP server provides add_visitor? +

add_visitor is provided by the API-Central MCP server (secure-ssid/centralmcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.