@zients/line-mcp-server

Multicast Flex Message

multicast_flex_message

Send a Flex Message to multiple LINE users (1-500) at once, specifying alternative notification text and a bubble or carousel container JSON for rich layout.

Instructions

Send a Flex Message (rich layout) to multiple LINE users at once (max 500 user IDs).

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "userIds": "<userIds>",
      "altText": "<altText>",
      "contents": "<contents>"
    },
    "name": "multicast_flex_message"
  }
}

Input Schema

Name	Required	Description
`altText`	Yes	Alternative text shown in push notifications (max 400 chars)
`userIds`	Yes	Array of User IDs to send to (1–500)
`contents`	Yes	Flex Message container JSON string (bubble or carousel)

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.1Sep 4, 2026

TDQS

A3.6/5.0

Behavior2/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations provided, the description carries the full burden of disclosing behavior. It only states the send action and the max user count, but does not mention side effects, error handling, permissions, or any operational details.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single, clear sentence that front-loads the main action and constraint. It is concise without unnecessary detail.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The description, combined with a complete schema, gives enough context for an agent to understand the tool's purpose and parameters. However, it lacks explicit information about the response or potential failure modes, which might be needed for full operational context.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The schema already provides descriptions for all three parameters, and the tool description does not add significant extra meaning beyond what is in the schema. It only restates that it sends a Flex Message, which is already clear from the schema's contents description.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the action (send) and the resource (Flex Message) to multiple LINE users, with a specific limit of 500 user IDs. It distinguishes itself from broadcast by implying a targeted multicast.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The usage is implied from the description (sending to multiple specific users) but not explicitly contrasted with alternatives like broadcast or single push. There is no explicit when-to-use or when-not-to-use guidance.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

Deploy Server