L Harness MCP Server

Run a self-hosted L Harness LINE Official Account CRM from an MCP client: friends, tags, scenarios, broadcasts

By 野田修一 (individual) TypeScript Local · stdio CRM and sales Communication

GitHub npm Website

45 popularity score ★ 614 ↓ 295/wk

Connect your client

Local (npm)

Add in one click

Add to Cursor Add to VS Code Add to LM Studio Add to Goose

Opens the app, which asks before it adds the server. Then replace each <NAME> in its settings with your value.

Or add it by command or config

It needs LINE_HARNESS_API_URL, LINE_HARNESS_API_KEY. Replace each <NAME> with your value.

Claude CodeTerminal

claude mcp add l-harness -e LINE_HARNESS_API_URL=<LINE_HARNESS_API_URL> -e LINE_HARNESS_API_KEY=<LINE_HARNESS_API_KEY> -- npx -y @line-harness/mcp-server@latest

Claude Desktopclaude_desktop_config.json

{
  "mcpServers": {
    "l-harness": {
      "command": "npx",
      "args": [
        "-y",
        "@line-harness/mcp-server@latest"
      ],
      "env": {
        "LINE_HARNESS_API_URL": "<LINE_HARNESS_API_URL>",
        "LINE_HARNESS_API_KEY": "<LINE_HARNESS_API_KEY>"
      }
    }
  }
}

Cursor~/.cursor/mcp.json

{
  "mcpServers": {
    "l-harness": {
      "command": "npx",
      "args": [
        "-y",
        "@line-harness/mcp-server@latest"
      ],
      "env": {
        "LINE_HARNESS_API_URL": "<LINE_HARNESS_API_URL>",
        "LINE_HARNESS_API_KEY": "<LINE_HARNESS_API_KEY>"
      }
    }
  }
}

VS Code.vscode/mcp.json

{
  "servers": {
    "l-harness": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "@line-harness/mcp-server@latest"
      ],
      "env": {
        "LINE_HARNESS_API_URL": "<LINE_HARNESS_API_URL>",
        "LINE_HARNESS_API_KEY": "<LINE_HARNESS_API_KEY>"
      }
    }
  }
}

Codex~/.codex/config.toml

[mcp_servers.l-harness]
command = "npx"
args = ["-y", "@line-harness/mcp-server@latest"]

[mcp_servers.l-harness.env]
LINE_HARNESS_API_URL = "<LINE_HARNESS_API_URL>"
LINE_HARNESS_API_KEY = "<LINE_HARNESS_API_KEY>"

Gemini CLITerminal

gemini mcp add --scope user -e LINE_HARNESS_API_URL=<LINE_HARNESS_API_URL> -e LINE_HARNESS_API_KEY=<LINE_HARNESS_API_KEY> l-harness npx -- -y @line-harness/mcp-server@latest

Settings 3

`LINE_HARNESS_API_URL`	Required: URL of your deployed L Harness Worker, e.g. https://<name>.workers.dev.
`LINE_HARNESS_API_KEY`	Required: API key issued in the L Harness admin for a staff user.
`LINE_HARNESS_ACCOUNT_ID`	Optional: Default LINE account ID when the deployment manages several accounts.

What it does

L Harness is an open-source CRM for LINE Official Accounts that you deploy to your own Cloudflare account (a Worker with a D1 database plus a Next.js admin site). The MCP server, published on npm as @line-harness/mcp-server, is a thin stdio wrapper around the project's TypeScript SDK: it calls your deployed Worker's HTTP API with a staff API key, and the Worker in turn talks to the LINE Messaging API.

Through it an assistant can look up friends and their details, read form answers, link clicks and conversion logs, see unanswered chats, and change most of the CRM: send a message to one friend, broadcast to everyone or a tag or segment, build step-message scenarios and enrol friends in them, manage tags, forms, rich menus, tracked links, auto-replies, message templates, traffic pools, entry routes, staff and ad platforms, and upload images or an HLS webinar video. It also exposes three read-only resources (line-harness://friends, line-harness://scenarios, line-harness://tags).

The MCP server page in the project wiki says it has 25 tools and lists 24, but the tool index at v0.24.0 registers 31; the extra ones (manage_auto_replies, manage_traffic_pools, manage_entry_routes, manage_message_templates, list_conversations, get_conversation, manage_webinar_video) appear only in the source. The client code also reads an optional LINE_HARNESS_ACCOUNT_ID that the docs do not mention, used as the default LINE account when you run several.

The project is by Shudesu (Shuichi Noda), not by LY Corporation, which runs LINE. The software is free under MIT; LINE message fees, Cloudflare usage and any domain are paid separately.

What it needs

Runtime	Node.js 20+

Node.js 20 or later for the MCP server (npx). A running L Harness deployment: a Cloudflare account (free tier works), a LINE Official Account with a Messaging API channel, and the Worker deployed with `npx create-line-harness` (that CLI needs Node.js 22+ and pnpm). You need the Worker's URL and an API key issued in the admin for a staff user. LINE delivery fees and Cloudflare usage are billed by those services.

Limits

It works only through an L Harness Worker you have deployed, not LINE directly. LINE_HARNESS_API_URL and LINE_HARNESS_API_KEY are checked on the first tool call, not at start, so a missing value shows up as every tool failing. send_message and broadcast turn URLs in a message into tracked links and text into a Flex message with a button by default (trackLinks defaults to true on send_message). list_conversations returns 50 by default, up to 200. The friends resource shows only the newest 20. manage_webinar_video does not encode video: you run ffmpeg yourself first and point it at the HLS output folder. On Cloudflare D1's free plan, queries fail once the daily read/write cap is reached.

Who it suits

Suits teams already running, or willing to self-host, L Harness on Cloudflare for a LINE Official Account in Japan or elsewhere, who want an assistant to check unanswered chats, pull friend and click data, or draft and send scenarios and broadcasts. Most tools change live data and several send messages to real customers, so it suits operators who review each send in their client. It is not a general LINE Messaging API server: without an L Harness deployment it does nothing, and someone on a paid LINE CRM such as L-step would need to migrate first.

Tools 31

list_friends: List friends, filtered by name, tag or metadata
get_friend_detail: Show one friend's profile, tags and metadata
get_form_submissions: Read answers submitted to a form
get_link_clicks: Show who clicked a tracked link and how often
get_conversion_logs: Read recorded conversion events
account_summary: Overview of friend count, tags and scenarios
list_crm_objects: Generic listing of CRM records by type
list_conversations: Unanswered chats, longest wait first
get_conversation: Read the message history with one friend
send_message: Send a text, image or Flex message to one friend
broadcast: Send a message to all friends, a tag or a segment
create_scenario: Create a step-message scenario
enroll_in_scenario: Put a friend into a scenario
create_form: Create a LIFF form
create_rich_menu: Create a rich menu, with an image
create_tracked_link: Create a click-tracking link
upload_image: Upload an image for use in messages
manage_friends: Count friends, edit metadata, switch a friend's rich menu
manage_tags: Create, edit and delete tags; add or remove them on friends
manage_scenarios: Edit, delete and list scenarios and their steps
manage_broadcasts: Create, edit, delete and send broadcasts, including segment sends
manage_rich_menus: List or delete rich menus and set the default
manage_forms: Create, edit and delete forms
manage_tracked_links: List or delete tracked links
manage_staff: Manage staff users and their roles
manage_ad_platforms: Manage ad platform connections for conversion tracking
manage_auto_replies: Keyword auto-reply rules: list, create, edit, delete
manage_message_templates: Saved text or Flex templates: list, create, edit, delete
manage_traffic_pools: Pools that spread new friends across LINE accounts
manage_entry_routes: Entry links that tag, start scenarios or route friends; funnel stats
manage_webinar_video: Upload a pre-encoded HLS webinar video from disk and publish it

Popularity

45 popularity score, on our list (the bar is 36)

★ 614 ↓ 295/wk

GitHub stars, whole repository	614	19.8 points
Stars in 30 days	+13	5.7 points
npm downloads, last week	295	19.8 points

It lives in the folder packages/mcp-server of shudesu/line-harness-oss, which holds more than this server. Its stars are the whole repository's, so in the score they never count for more than its own downloads.

Measured 2026-11-08. How the score works.

Where it is published

Code	shudesu/line-harness-oss/packages/mcp-server ★ 614, the whole repository
npm	@line-harness/mcp-server 0.24.0, 2026-09-02

What it can reach

Runs	On your machine
Reaches	Your account at a service, Sends messages, The internet, Files on your machine
Changes things	Yes: it can write, send, create or delete
Sign-in	An API key or token
Licence	MIT (npm)
Last code change	2026-10-26

Runs on your machine over stdio and sends requests to the L Harness Worker URL you give, authenticated with a staff API key; what it can do follows that staff user's role (Owner, Admin or Staff). Most tools write: they send LINE messages and broadcasts to real friends, and create or delete scenarios, tags, forms, rich menus, staff and other records. send_message and broadcast take no confirmation argument, so any check before sending is the MCP client's own approval prompt. manage_webinar_video reads a video folder from the local machine and uploads it to your deployment. The data itself lives in your Cloudflare D1 database and passes through the LINE Messaging API.

Over time

GitHub stars, whole repository 614 +13 (+2 %)

615601

9 Oct 20268 Nov 2026

npm downloads a week 295 −495 (−63 %)

1.4k65

6 Apr 20268 Nov 2026

Before the site measured it, read from npm's daily download counts.

Popularity score 45 −8 (−15 %)

5337

9 Oct 20268 Nov 2026

What is rising across the directory

Sources

Page checked 2026-10-15.

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Connect your client

Add in one click

Or add it by command or config

Settings 3

What it does

What it needs

Limits

Who it suits

Tools 31

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