list_emoji

THE RISK

Low Risk

Why list_emoji needs a policy

This tool queries and retrieves emoji metadata from the Zulip server without creating, modifying, deleting, or executing any operations. It is a pure read operation with minimal security impact—emoji lists are typically public or low-sensitivity data on communication platforms.

From the tool's definition Tool name is 'list_emoji' and description states 'Search custom emoji available on this Zulip server.' The verb 'search' combined with 'list' indicates data retrieval with no side effects.

Documented attack patterns abuse exactly the kind of access list_emoji gives an agent:

POLICY

How to control list_emoji

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

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "list_emoji": {}
  }
}

list_emoji 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 Zulip — 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 →

Free to start. No card required.

EXPLORE

Related tools and policies

More Zulip tools

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All 27 Zulip 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 list_emoji

What does the list_emoji tool do? +

Search custom emoji available on this Zulip server. It is categorised as a Read tool in the Zulip MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on list_emoji? +

Register the Zulip MCP server in PolicyLayer and add a rule for list_emoji: 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 Zulip. Nothing to install.

What risk level is list_emoji? +

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

Can I rate-limit list_emoji? +

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

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

list_emoji is provided by the Zulip MCP server (windborne/zulipmcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Zulip tool call.

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

CHECK YOUR STACK →