pin_message · Tg MCP: Risk & Policy

WHAT IT DOES

What pin_message does on Tgmcp

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

WHY IT NEEDS A POLICY

Why pin_message needs a policy

Pinning a message modifies chat metadata and visibility settings but does not delete, destroy, or irreversibly alter data. It is reversible (can be unpinned), distinguishing it from Destructive actions. While it affects shared chat state, the blast radius is limited to message organization rather than data loss or financial impact.

From the tool's definition Tool description: 'Pin a message in a chat.' The action modifies chat state by changing message prominence, which is reversible (messages can be unpinned).

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

pin_message Rate-limited

pin_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": {
    "pin_message": {
      "limits": [
        {
          "counter": "pin_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 Tgmcp, so you can run agents against it safely.

FAQ

Questions about pin_message

What does the pin_message tool do? +

Pin a message in a chat. It is categorised as a Write tool in the Tgmcp MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on pin_message? +

Register the Tg MCP server in PolicyLayer and add a rule for pin_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 Tgmcp. Nothing to install.

What risk level is pin_message? +

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

Can I rate-limit pin_message? +

Yes. Add a rate_limit block to the pin_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 pin_message completely? +

Set action: deny in the PolicyLayer policy for pin_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 pin_message? +

pin_message is provided by the Tg MCP server (oevortex/tgmcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.