start_typing · Bluebubbles MCP: Risk & Policy

WHAT IT DOES

What start_typing does on Bluebubbles

AI agents invoke start_typing to trigger actions in Bluebubbles. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why start_typing needs a policy

This tool executes an operation that modifies the state of a chat interface (displaying a typing indicator) visible to other participants. It is not merely reading data (Read), nor is it creating/modifying message content (Write), nor is it destructive or financial. It is an Execute category tool because it triggers an external action whose behavioral effects depend on the argument (which chat).

From the tool's definition Tool performs an action 'show a typing indicator in a chat (visible to the other person)' which triggers an external operation with effects that depend on which chat is targeted.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

start_typing Rate-limited

start_typing stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "start_typing": {
      "limits": [
        {
          "counter": "start_typing_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Bluebubbles, so you can run agents against it safely.

FAQ

Questions about start_typing

What does the start_typing tool do? +

Show a typing indicator in a chat (visible to the other person). It is categorised as a Execute tool in the Bluebubbles MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on start_typing? +

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

What risk level is start_typing? +

start_typing is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit start_typing? +

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

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

start_typing is provided by the Bluebubbles MCP server (metaember/bluebubbles-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.