messages_trigger

THE RISK

High Risk

Why messages_trigger needs a policy

This tool triggers external operations (displaying messages in a presentation control system) whose effects are determined by arguments (which message, what token values). The outcome depends entirely on how an AI agent uses it. While not destructive or financial, it performs an action with real-world side effects in a live presentation context, making it Execute rather than Write or Read.

From the tool's definition Tool name 'messages_trigger' and description 'Trigger (show) a specific message with optional token values' indicate the tool executes an action that causes a presentation message to be displayed, affecting the state of the ProPresenter application and what…

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

POLICY

How to control messages_trigger

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

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "messages_trigger": {
      "limits": [
        {
          "counter": "messages_trigger_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

messages_trigger stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

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

RATE-LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Propresenter tools

Destructive clear_layer Clear a specific layer (audio, props, messages, announcements, slide, media, video_input) Destructive messages_delete Delete a specific message Destructive props_clear Clear a specific prop from display Destructive props_delete Delete a specific prop Destructive props_delete_collection Delete a specific prop collection Destructive stage_delete_layout Delete a specific stage layout Execute clear_trigger_group Trigger a specific clear group Execute props_pause_auto_clear Pause auto-clear for a specific prop

All 177 Propresenter tools →

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Go deeper

High-risk tools in Propresenter → Every high-risk tool this server exposes, in one view.
All high-risk MCP tools → Every high-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Agent sandbox → Bounding what an agent can execute and where the boundary should sit.
Least privilege for MCP → Granting agents the minimum tool surface the task needs.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about messages_trigger

What does the messages_trigger tool do? +

Trigger (show) a specific message with optional token values. It is categorised as a Execute tool in the Propresenter MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on messages_trigger? +

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

What risk level is messages_trigger? +

messages_trigger is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit messages_trigger? +

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

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

messages_trigger is provided by the Propresenter MCP server (@alxpark/propresenter-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Propresenter tool call.

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

CHECK YOUR STACK →