message_sitter · Rover MCP Server MCP: Risk & Policy

WHAT IT DOES

What message_sitter does on Rover MCP Server

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

WHY IT NEEDS A POLICY

Why message_sitter needs a policy

The tool creates new data (messages) in the Rover system. While messaging is generally low-risk, the medium severity accounts for potential misuse such as sending fraudulent communications, impersonation, or harassment to sitters, which could have tangible consequences for user relationships and platform trust.

From the tool's definition Tool description states 'Send a message to a sitter on Rover', which creates new communication data on the platform. This is a write operation that creates reversible artifacts (messages can typically be deleted or edited on messaging platforms).

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

message_sitter Rate-limited

message_sitter 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": {
    "message_sitter": {
      "limits": [
        {
          "counter": "message_sitter_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 Rover MCP Server, so you can run agents against it safely.

FAQ

Questions about message_sitter

What does the message_sitter tool do? +

Send a message to a sitter on Rover. Requires being logged in. It is categorised as a Write tool in the Rover MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on message_sitter? +

Register the Rover MCP Server MCP server in PolicyLayer and add a rule for message_sitter: 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 Rover MCP Server. Nothing to install.

What risk level is message_sitter? +

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

Can I rate-limit message_sitter? +

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

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

message_sitter is provided by the Rover MCP Server MCP server (markswendsen-code/mcp-rover). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.