zulip_subscribe_to_stream · Zulip MCP Server MCP

WHAT IT DOES

What zulip_subscribe_to_stream does on Zulip MCP Server

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

WHY IT NEEDS A POLICY

Why zulip_subscribe_to_stream needs a policy

This tool modifies state by subscribing the user/agent to a stream and may create streams as a side effect. These are write operations because they create or modify data (stream creation and subscription records) in a reversible manner.

From the tool's definition The tool description explicitly states it 'Subscribe to a Zulip stream. Creates the stream if it does not exist.' This involves creating new resources (streams) and modifying subscription state, which are reversible write operations.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

zulip_subscribe_to_stream Rate-limited

zulip_subscribe_to_stream 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": {
    "zulip_subscribe_to_stream": {
      "limits": [
        {
          "counter": "zulip_subscribe_to_stream_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 Zulip MCP Server, so you can run agents against it safely.

FAQ

Questions about zulip_subscribe_to_stream

What does the zulip_subscribe_to_stream tool do? +

Subscribe to a Zulip stream. Creates the stream if it does not exist. It is categorised as a Write tool in the Zulip MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on zulip_subscribe_to_stream? +

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

What risk level is zulip_subscribe_to_stream? +

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

Can I rate-limit zulip_subscribe_to_stream? +

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

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

zulip_subscribe_to_stream is provided by the Zulip MCP Server MCP server (prixite/zulip-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.