machines_heartbeat · Todos MCP: Risk & Policy

WHAT IT DOES

What machines_heartbeat does on Todos

AI agents use machines_heartbeat to create or update resources in Todos — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Todos environment.

WHY IT NEEDS A POLICY

Why machines_heartbeat needs a policy

This tool modifies machine metadata (last-seen timestamps and topology information) but does not delete data, execute code, move money, or cause irreversible changes. The updates are reversible and represent standard state maintenance typical of heartbeat/health-check mechanisms. The scope is limited to metadata rather than critical task data, warranting 'low' severity.

From the tool's definition Tool name 'machines_heartbeat' with description 'Update local last-seen and topology metadata for a machine' indicates modification of metadata records. The term 'Update' directly indicates a write operation.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

machines_heartbeat Rate-limited

machines_heartbeat 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.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "machines_heartbeat": {
      "limits": [
        {
          "counter": "machines_heartbeat_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Todos, so you can run agents against it safely.

FAQ

Questions about machines_heartbeat

What does the machines_heartbeat tool do? +

Update local last-seen and topology metadata for a machine. It is categorised as a Write tool in the Todos MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on machines_heartbeat? +

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

What risk level is machines_heartbeat? +

machines_heartbeat is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit machines_heartbeat? +

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

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

machines_heartbeat is provided by the Todos MCP server (@hasna/todos). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.