Line.OpenApi.Tools 0.1.0-preview

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Line.OpenApi.Tools — CLI / MCP tool for LINE

A dotnet global tool (command name line) for operating the LINE Platform from your local machine. Built on top of the Line.OpenApi.* client libraries, it exposes the same functionality both as CLI subcommands and as MCP server tools.

• CLI — run from a terminal by a human (line message push ...)
• MCP server — called by AI agents (Claude Desktop / Claude Code, etc.) via line mcp over stdio

Both share the same service layer, so behavior is identical.

Features

Target framework: net10.0.

Installation

Publishing to NuGet.org is in preparation (0.1.0-preview). Once published:

dotnet tool install -g Line.OpenApi.Tools

Run from local source (inside this repository):

dotnet run --project tools/Line.OpenApi.Tools -- <command> ...
# e.g.
dotnet run --project tools/Line.OpenApi.Tools -- --help

Quick start

1. Configure credentials (profiles)

Credentials are stored per profile in ~/.line/config.json (%USERPROFILE%\.line\config.json on Windows).

# Fastest start with a static token
line config set default --token "YOUR_CHANNEL_ACCESS_TOKEN"

# Or set the key material used for token issuance
line config set default \
  --channel-id "1234567890" \
  --kid "your-key-id" \
  --private-key "~/.line/keys/default.pem" \
  --secret "YOUR_CHANNEL_SECRET"

line config list          # list profiles (* marks the default)
line config get default   # show a profile (secrets masked)
line config use staging   # switch the default profile

Security: the config stores secrets in plain text. On Unix it is created with 0600 (owner read/write only). On Windows it inherits the user-profile ACL (a warning is printed on save). The private key is referenced by path only — its contents are never stored in the config.

2. Try it

line bot info                                   # bot information
line message push --to U0123... --text "Hello"  # push a message
line liff list                                  # list LIFF apps

Credential resolution order

Each command resolves credentials in the following priority (top wins):

1. Command-line arguments (--channel-token / --channel-id / --secret / --private-key / --kid)
2. Environment variables
3. Profile (--profile <name>, or the default profile)

Environment variables

Global options (all commands)

Command reference

A. Token management — line token

# Issue (v2.1 by default; --kind stateless for a stateless token)
line token issue --kind v2.1 --days 30 \
  --channel-id 123 --kid KID --private-key ./key.pem

line token issue --store          # issue and store into the resolved profile
line token verify --token <t>     # check validity and remaining lifetime
line token revoke --token <t>     # revoke (requires --channel-id / --secret)

• Issuance requires the channel id, key id, and private key (PEM). The CLI builds and sends an RS256 JWT assertion.
• On the CLI the issued token is written to stdout and metadata to stderr (pipe-friendly). Use --store to save it into the resolved profile.

B. Message send & bot lookup — line message / line bot

Message content is provided via one of --text, --flex <file>, or --messages <file>.

line message push --to <id> --text "Hello"
line message push --to <id> --flex ./flex.json --alt-text "Notice"
line message push --to <id> --messages ./messages.json     # a messages-array JSON verbatim
line message multicast --to id1,id2,id3 --text "To many"
line message broadcast --text "To everyone"
line message reply --reply-token <token> --text "Reply"
line message content <messageId> -o ./image.jpg           # download a message's binary content

line bot info
line bot quota                # send quota limit
line bot quota consumption    # this month's consumption
line bot profile <userId>

• --flex takes a Flex message contents JSON and automatically wraps it into a Flex message with altText.
• --messages sends a [{ "type": "text", "text": "..." }, ...] messages array as-is.
• content is fetched from the data host (api-data.line.me); the facade routes it automatically.

C. Webhook development — line webhook

# Local receiver (verifies the signature and prints incoming events)
line webhook listen --port 5000

# Verify a stored payload's signature and summarize its events
line webhook verify --body ./payload.json --signature <x-line-signature>

# Replay a stored payload to a local app (no signature added; destination not validated)
line webhook replay --body ./payload.json --to http://localhost:5000/webhook

• Signature verification requires the channel secret (profile / --secret).
• Combine listen with an external tunnel (cloudflared / ngrok, etc.) to receive real webhooks from LINE. The tunnel itself is not bundled.

D. LIFF management — line liff

line liff list
line liff add --file ./app.json               # add from a LIFF app definition JSON
line liff update <liffId> --file ./app.json
line liff delete <liffId>

Exit codes

Use as an MCP server

line mcp starts an MCP server over stdio so AI agents can operate LINE as tools.

line mcp                       # all tools enabled
line mcp --read-only           # expose read-only tools only
line mcp --allow-secret-output # allow token issue to return the raw token (withheld by default)
line mcp --allow-remote-replay # allow non-loopback destinations for webhook replay (loopback-only by default)

Tool list

CLI commands are exposed as line_<area>_<verb> (except webhook listen).

• Read-only (available even under --read-only): line_bot_info / line_bot_quota / line_bot_quota_consumption / line_bot_profile / line_liff_list / line_token_verify / line_webhook_verify / line_ping
• Mutating (excluded under --read-only): line_message_push / line_message_multicast / line_message_broadcast / line_message_reply / line_liff_add / line_liff_update / line_liff_delete / line_token_issue / line_token_revoke / line_webhook_replay

Each tool accepts an optional profile argument; credentials are resolved from the profile.

Security design (MCP)

MCP tool results are assumed to enter the model's context (sent to the LLM provider, conversation history, logs), so the following protections are built in:

• line_token_issue does not return the raw token by default. The issued token is stored into the local profile and the result contains only metadata (tokenType / expiresInSeconds / keyId / maskedToken / storedProfile). Subsequent send tools operate via the stored profile. To obtain the raw token, start the server with --allow-secret-output and pass reveal: true in the tool call.
• line_webhook_replay allows loopback destinations only by default (SSRF mitigation). Remote destinations require --allow-remote-replay.
• Mutating / sending tools state their side effects in the description.

Register with Claude Code

claude mcp add line -- line mcp
# read-only registration
claude mcp add line -- line mcp --read-only

Register with Claude Desktop (claude_desktop_config.json)

{
  "mcpServers": {
    "line": {
      "command": "line",
      "args": ["mcp"]
    }
  }
}

Build from source

dotnet build tools/Line.OpenApi.Tools/Line.OpenApi.Tools.csproj
dotnet test  tests/Line.OpenApi.Tools.Tests/Line.OpenApi.Tools.Tests.csproj

Related documentation

• Specification: docs/CLI-MCP-tool-spec.md
• Core libraries: repository root README.md

License

MIT (see LICENSE at the repository root).