reminders.list_sources

THE RISK

Low Risk

Why reminders.list_sources needs a policy

This tool retrieves metadata about reminder sources without creating, modifying, or deleting any data. It is a simple enumeration operation analogous to 'list' or 'get'. The information returned (account/source identifiers) has minimal sensitivity in isolation and the operation is non-destructive and reversible. Low severity reflects the limited blast radius if an agent misuses this tool.

From the tool's definition Tool name contains 'list' and description states 'List reminder sources/accounts' — a query operation with no side effects.

Documented attack patterns abuse exactly the kind of access reminders.list_sources gives an agent:

POLICY

How to control reminders.list_sources

PolicyLayer is an MCP gateway — it sits between your AI agents and Nucleus Apple, and nothing reaches the server without passing your rules. This is the rule we recommend for reminders.list_sources:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "reminders.list_sources": {}
  }
}

reminders.list_sources is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.

Create a free account and register Nucleus Apple — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

CAP THIS TOOL →

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EXPLORE

Related tools and policies

More Nucleus Apple tools

Destructive calendar.delete_event Delete a calendar event. Destructive notes.delete_note Delete a note. Destructive reminders.delete_reminder Delete a reminder. Write notes.save_attachment Export an attachment to a file path. Write calendar.create_event Create a calendar event. Write calendar.update_event Update an existing calendar event. Write notes.add_attachment Add attachment(s) to a note from local file paths. Write notes.create_note Create a new note.

All 30 Nucleus Apple tools →

Read tools on other servers

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about reminders.list_sources

What does the reminders.list_sources tool do? +

List reminder sources/accounts. It is categorised as a Read tool in the Nucleus Apple MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on reminders.list_sources? +

Register the Nucleus Apple MCP server in PolicyLayer and add a rule for reminders.list_sources: 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 Nucleus Apple. Nothing to install.

What risk level is reminders.list_sources? +

reminders.list_sources is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit reminders.list_sources? +

Yes. Add a rate_limit block to the reminders.list_sources 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 reminders.list_sources completely? +

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

reminders.list_sources is provided by the Nucleus Apple MCP server (zish-rob-crur/nucleus-apple-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Nucleus Apple tool call.

Start from Nucleus Apple, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →