Send a direct message (DM) to one or more users.
AI agents use send_direct_message to create or update resources in Zulip — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Zulip environment.
This tool creates new data (direct messages) in Zulip, which is reversible through deletion or editing. It is a Write operation. Severity is medium because misuse could result in spam, harassment, or unwanted communications to users, but the impact is limited in scope (one or more recipients) and reversible. The tool does not execute code, delete data, or move financial resources.
From the tool's definition Tool name 'send_direct_message' and description 'Send a direct message (DM) to one or more users' indicate creation of new message content.
Documented attack patterns abuse exactly the kind of access send_direct_message gives an agent:
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 send_direct_message:
{
"version": "1",
"default": "deny",
"tools": {
"send_direct_message": {
"limits": [
{
"counter": "send_direct_message_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}send_direct_message 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.
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Send a direct message (DM) to one or more users. It is categorised as a Write tool in the Zulip MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Zulip MCP server in PolicyLayer and add a rule for send_direct_message: 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.
send_direct_message is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the send_direct_message 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.
Set action: deny in the PolicyLayer policy for send_direct_message. 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.
send_direct_message 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.
Start from Zulip, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
27 Zulip tools catalogued and risk-classified — across an index of 43,000+ MCP servers.