AI agents invoke timers_stop to trigger actions in Propresenter. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.
Stopping a timer is an action that modifies the runtime state of the presentation software and affects live playback/scheduling. It does not permanently delete data (Destructive), does not move money (Financial), and does not merely read state (Read). It executes a command with real-world consequences for the presentation workflow, making it Execute-category.
From the tool's definition Tool name is 'timers_stop' and description states 'Stop a specific timer' — this triggers an external operation (stopping a timer in ProPresenter 7) whose effect depends on which timer is targeted.
Documented attack patterns abuse exactly the kind of access timers_stop gives an agent:
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 timers_stop:
{
"version": "1",
"default": "deny",
"tools": {
"timers_stop": {
"limits": [
{
"counter": "timers_stop_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}timers_stop 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.
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Stop a specific timer. 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.
Register the Propresenter MCP server in PolicyLayer and add a rule for timers_stop: 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.
timers_stop is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the timers_stop 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 timers_stop. 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.
timers_stop 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.
Start from Propresenter, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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177 Propresenter tools catalogued and risk-classified — across an index of 43,000+ MCP servers.