close_thread · Twist MCP: Risk & Policy

WHAT IT DOES

What close_thread does on Twist

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

WHY IT NEEDS A POLICY

Why close_thread needs a policy

This is a Write operation because it modifies data reversibly—changing a thread's closed status. It does not delete data (Destructive), execute arbitrary code (Execute), move money (Financial), or merely read data (Read). While the effect is permanent during the thread's lifecycle, the action itself is not irreversible in the destructive sense; threads remain accessible and could theoretically be reopened.

From the tool's definition The tool 'close_thread' modifies the state of an existing thread by marking it as closed, which changes the thread's status and prevents future replies. The description states it 'marks a thread as closed' and adds a closing message automatically.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

close_thread Rate-limited

close_thread 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": {
    "close_thread": {
      "limits": [
        {
          "counter": "close_thread_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 Twist, so you can run agents against it safely.

FAQ

Questions about close_thread

What does the close_thread tool do? +

Close an existing Twist thread with an optional closing message. This tool marks a thread as closed, preventing further replies while keeping the thread accessible for reference. A closing message is automatically added to indicate the thread has been closed. Example response: Successfully closed thread: - Thread ID: 789012 - Closing message:. It is categorised as a Write tool in the Twist MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on close_thread? +

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

What risk level is close_thread? +

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

Can I rate-limit close_thread? +

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

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

close_thread is provided by the Twist MCP server (twist-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.