update_membership · Groupme MCP: Risk & Policy

WHAT IT DOES

What update_membership does on Groupme

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

WHY IT NEEDS A POLICY

Why update_membership needs a policy

This tool creates or modifies data (nickname metadata) in a reversible manner. It does not delete data (not Destructive), execute external code (not Execute), move money (not Financial), or retrieve-only information (not Read). The blast radius is minimal: a misused nickname update affects only the user's display name in that group, easily corrected by updating again. This is a classic Write operation.

From the tool's definition Tool description states 'Update your nickname in a group' — this modifies user profile data within a group context reversibly.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_membership Rate-limited

update_membership 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": {
    "update_membership": {
      "limits": [
        {
          "counter": "update_membership_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 Groupme, so you can run agents against it safely.

FAQ

Questions about update_membership

What does the update_membership tool do? +

Update your nickname in a group. It is categorised as a Write tool in the Groupme MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on update_membership? +

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

What risk level is update_membership? +

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

Can I rate-limit update_membership? +

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

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

update_membership is provided by the Groupme MCP server (kalebjs/groupme-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.