push_flex_message · LINE Bot MCP Server MCP: Risk & Policy

WHAT IT DOES

What push_flex_message does on LINE Bot MCP Server

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

WHY IT NEEDS A POLICY

Why push_flex_message needs a policy

The tool sends (creates) messages to users through LINE, which is a reversible write operation. While it communicates with users, the message itself can be deleted or the interaction reversed. It does not execute code, delete data irreversibly, transfer money, or perform destructive operations.

From the tool's definition Tool description states it 'Push a highly customizable flex message to a user via LINE' - this creates/sends a new message, which is a write operation that modifies the state of LINE conversations by adding content.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

push_flex_message Rate-limited

push_flex_message 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": {
    "push_flex_message": {
      "limits": [
        {
          "counter": "push_flex_message_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 LINE Bot MCP Server, so you can run agents against it safely.

FAQ

Questions about push_flex_message

What does the push_flex_message tool do? +

Push a highly customizable flex message to a user via LINE. Supports both bubble (single container) and carousel. It is categorised as a Write tool in the LINE Bot 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 push_flex_message? +

Register the LINE Bot MCP Server MCP server in PolicyLayer and add a rule for push_flex_message: 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 LINE Bot MCP Server. Nothing to install.

What risk level is push_flex_message? +

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

Can I rate-limit push_flex_message? +

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

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

push_flex_message is provided by the LINE Bot MCP Server MCP server (tndfame/mcp_management). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.