ack_message · Claude Sync MCP: Risk & Policy

WHAT IT DOES

What ack_message does on Claude Sync

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

WHY IT NEEDS A POLICY

Why ack_message needs a policy

Acknowledging a message modifies its state in the SQLite persistence layer (e.g., marking it as read/processed). This is a reversible write operation with low blast radius — misuse could cause messages to be incorrectly marked as processed, but it does not delete data or trigger external operations.

From the tool's definition 'Acknowledge a message after processing' — marks a message as acknowledged, which is a state update/modification

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

ack_message Rate-limited

ack_message 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": {
    "ack_message": {
      "limits": [
        {
          "counter": "ack_message_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 Claude Sync, so you can run agents against it safely.

FAQ

Questions about ack_message

What does the ack_message tool do? +

Acknowledge a message after processing. It is categorised as a Write tool in the Claude Sync MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on ack_message? +

Register the Claude Sync MCP server in PolicyLayer and add a rule for ack_message: 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 Claude Sync. Nothing to install.

What risk level is ack_message? +

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

Can I rate-limit ack_message? +

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

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

ack_message is provided by the Claude Sync MCP server (the-firmament/claude-sync). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.