coord_heartbeat · Session Coord MCP: Risk & Policy

WHAT IT DOES

What coord_heartbeat does on Session Coord

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

WHY IT NEEDS A POLICY

Why coord_heartbeat needs a policy

This tool updates mutable session metadata (heartbeat timestamp, status, current task assignment) but does not delete data or trigger external operations with unknown side effects. The updates are reversible and scoped to session coordination state. It is Write rather than Execute because it performs specific state mutations rather than arbitrary code execution.

From the tool's definition Tool description states 'Refresh a session heartbeat and optionally update status/current task' — the 'update' capability modifies session state reversibly.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

coord_heartbeat Rate-limited

coord_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": {
    "coord_heartbeat": {
      "limits": [
        {
          "counter": "coord_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 Session Coord, so you can run agents against it safely.

FAQ

Questions about coord_heartbeat

What does the coord_heartbeat tool do? +

Refresh a session heartbeat and optionally update status/current task. It is categorised as a Write tool in the Session Coord MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on coord_heartbeat? +

Register the Session Coord MCP server in PolicyLayer and add a rule for coord_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 Session Coord. Nothing to install.

What risk level is coord_heartbeat? +

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

Can I rate-limit coord_heartbeat? +

Yes. Add a rate_limit block to the coord_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 coord_heartbeat completely? +

Set action: deny in the PolicyLayer policy for coord_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 coord_heartbeat? +

coord_heartbeat is provided by the Session Coord MCP server (lingfeng-vels/session-coord-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.