create_contact · Nexus Core MCP: Risk & Policy

WHAT IT DOES

What create_contact does on Nexus Core

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

WHY IT NEEDS A POLICY

Why create_contact needs a policy

This tool creates (writes) new data in Google Contacts reversibly — contacts can be edited or deleted later. It does not execute arbitrary code, delete data irreversibly, move money, or read sensitive information without modification.

From the tool's definition Tool description states 'Create a new Google contact' — the verb 'create' explicitly indicates a write operation that adds a new record to the contact database.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

create_contact Rate-limited

create_contact 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": {
    "create_contact": {
      "limits": [
        {
          "counter": "create_contact_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 Nexus Core, so you can run agents against it safely.

FAQ

Questions about create_contact

What does the create_contact tool do? +

Create a new Google contact. groups = list of group names (resolved server-side). It is categorised as a Write tool in the Nexus Core MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on create_contact? +

Register the Nexus Core MCP server in PolicyLayer and add a rule for create_contact: 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 Nexus Core. Nothing to install.

What risk level is create_contact? +

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

Can I rate-limit create_contact? +

Yes. Add a rate_limit block to the create_contact 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 create_contact completely? +

Set action: deny in the PolicyLayer policy for create_contact. 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 create_contact? +

create_contact is provided by the Nexus Core MCP server (noumenon-ai/nexus-core). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.