start_timer

Start a timer. duration format: HH:MM:SS or number of seconds.

SERVERHa Nexus Agent SOURCEfistacho/ha-nexus-agent

High RISK CLASS

Category Execute

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/fistacho-ha-nexus-agent/start-timer.md

WHAT IT DOES

What start_timer does on Ha Nexus Agent

AI agents invoke start_timer to trigger actions in Ha Nexus Agent. 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.

RISK

Why start_timer is rated High

This tool executes a command that initiates a timer in Home Assistant. While the action itself is benign and has no destructive or financial consequences, it is still an Execute category because it runs an external operation whose effects depend on the provided arguments (the duration).

From the tool's definition Tool explicitly performs an action ('Start a timer') that triggers external behavior in the smart home system. The tool accepts a duration parameter and initiates a timed operation, which is an execution trigger rather than data retrieval or modification.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs start_timer safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Ha Nexus Agent, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For start_timer, this is the rule to start with:

start_timer Rate-limited

start_timer 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.

View as policy code

policy.json

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

RATE-LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Ha Nexus Agent, apply this rule, and every start_timer call is checked against it from then on.

FAQ

Questions about start_timer

What does the start_timer tool do? +

Start a timer. duration format: HH:MM:SS or number of seconds. It is categorised as a Execute tool in the Ha Nexus Agent MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on start_timer? +

Register the Ha Nexus Agent MCP server in PolicyLayer and add a rule for start_timer: 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 Ha Nexus Agent. Nothing to install.

What risk level is start_timer? +

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

Can I rate-limit start_timer? +

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

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

start_timer is provided by the Ha Nexus Agent MCP server (fistacho/ha-nexus-agent). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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