heartbeat · Agent-Comm-Hub MCP: Risk & Policy

WHAT IT DOES

What heartbeat does on Agent-Comm-Hub

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

WHY IT NEEDS A POLICY

Why heartbeat needs a policy

The heartbeat function creates or updates agent metadata (online status, trust score accumulation) as a side effect. This is a reversible state modification - agents can go offline and trust scores reflect cumulative counts that change with each heartbeat. It does not execute arbitrary code, delete data irreversibly, or move money.

From the tool's definition Tool name 'heartbeat' with description indicating it '上报 Agent 心跳，维持在线状态并累积信任分' (reports agent heartbeat, maintains online status, and accumulates trust_score). This modifies agent state (online/offline status, trust_score counter) reversibly.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

heartbeat Rate-limited

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": {
    "heartbeat": {
      "limits": [
        {
          "counter": "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 Agent-Comm-Hub, so you can run agents against it safely.

FAQ

Questions about heartbeat

What does the heartbeat tool do? +

上报 Agent 心跳，维持在线状态并累积信任分。Agent 上线后应每 30 秒调用一次。超过 90 秒无心跳将自动标记为离线。连续在线心跳每 3 次自动增加 1 点 trust_score（上限 100）。. It is categorised as a Write tool in the Agent-Comm-Hub MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on heartbeat? +

Register the Agent-Comm-Hub MCP server in PolicyLayer and add a rule for 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 Agent-Comm-Hub. Nothing to install.

What risk level is heartbeat? +

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

Can I rate-limit heartbeat? +

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

Set action: deny in the PolicyLayer policy for 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 heartbeat? +

heartbeat is provided by the Agent-Comm-Hub MCP server (liuboacean/agent-comm-hub). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.