Low Risk

get_message_by_id

Get a specific message by its ID.

How to control get_message_by_id ↓

What get_message_by_id does on Zulip

AI agents call get_message_by_id to retrieve information from Zulip without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

Low Risk

Why get_message_by_id needs a policy

This tool retrieves a single message from Zulip by ID. It performs a read-only query operation with no capability to modify, delete, or execute actions. The blast radius of misuse is minimal—an agent could read messages it shouldn't access, but this is a data confidentiality risk rather than an operational one. Classified as Read with low severity.

From the tool's definition Tool name 'get_message_by_id' and description 'Get a specific message by its ID' indicate a retrieval operation with no side effects.

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

How to control get_message_by_id

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 get_message_by_id:

policy.json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "get_message_by_id": {}
  }
}

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

  1. Create a free account and register Zulip — nothing to install.
  2. Add this policy — paste it, or build it visually.
  3. Point your MCP client (Claude, Cursor, anything) at your gateway URL.
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Related tools and policies

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Questions about get_message_by_id

What does the get_message_by_id tool do? +

Get a specific message by its ID. 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 get_message_by_id? +

Register the Zulip MCP server in PolicyLayer and add a rule for get_message_by_id: 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 get_message_by_id? +

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

Can I rate-limit get_message_by_id? +

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

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

get_message_by_id 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.

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27 Zulip tools catalogued and risk-classified — across an index of 43,000+ MCP servers.

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