update_activity · REP Helper MCP: Risk & Policy

WHAT IT DOES

What update_activity does on REP Helper

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

WHY IT NEEDS A POLICY

Why update_activity needs a policy

This tool modifies existing activity records reversibly. While not destructive (changes can be undone via further updates), it carries medium severity because incorrect activity updates could affect tax documentation and financial claims (REPS/STR material participation for IRS purposes).

From the tool's definition Tool description states 'Update an existing activity' which is a reversible modification of data. The context involves tracking rental hours for tax documentation purposes.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_activity Rate-limited

update_activity 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_activity": {
      "limits": [
        {
          "counter": "update_activity_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 REP Helper, so you can run agents against it safely.

FAQ

Questions about update_activity

What does the update_activity tool do? +

Update an existing activity. Only include fields you want to change. It is categorised as a Write tool in the REP Helper 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_activity? +

Register the REP Helper MCP server in PolicyLayer and add a rule for update_activity: 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 REP Helper. Nothing to install.

What risk level is update_activity? +

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

Can I rate-limit update_activity? +

Yes. Add a rate_limit block to the update_activity 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_activity completely? +

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

update_activity is provided by the REP Helper MCP server (rephelper-ai/mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.