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Line9

by line9.ai · remote · no sign-in to list tools · v0.4.4 · published by ai.line9

Render Mermaid with Line9 layout in your assistant.

Changes · 1
CompareRegistry entry

3 tools: 1 change things and 2 only read.

Scanned Oct 21, 2026

No check matched anything in the tool definitions. No finding is not a safety guarantee. How the checks work.

claude mcp add --transport http diagrams https://mcp.line9.ai/mcp

Tools

Open a tool for its reasons and full description. Descriptions are the publisher's own words, shown as they are.

3 tools

Changes things 1Claude Code: ask
  • render_diagramRender Mermaid source with Line9's layout engine.No findings

    Why it is in this group

    • Nothing in its name or description says what it does, so it is counted as a write.
    • The server marks it read-only (readOnlyHint: true), but an annotation never lowers a class.
    Description, as the server wrote it
    Render Mermaid source with Line9's layout engine. Call this whenever you write or change Mermaid and the user should see the result. Flowcharts and sequence diagrams get Line9's layout; other Mermaid kinds are rendered with Mermaid's own layout and flagged as such. Returns a short verdict — kind, size, warnings, or a parse error with its line and column — plus an "Open in Line9" link. On a parse error, fix the named line and call again. Assistants that support MCP Apps show the diagram in a panel; there, do not paste the SVG or repeat the source in your reply. In an assistant with no panel (a terminal or editor), reply with the verdict line and the `open_url` link — that link is the only way the user sees the diagram. Write flowcharts as `flowchart LR` unless the user asks for top-to-bottom; chat panels are wide and short. No sign-in needed; renders carry a small Line9 mark unless the user is signed in to Line9 Pro. Set theme, orientation, spacing and legend in the source itself (`line9:` frontmatter; `flowchart LR`), never as arguments. This connector cannot publish or save. To publish, the user opens the diagram in Line9 (the `open_url` link) and publishes there — not with the Line9 CLI.

    Annotations the server declares

    • readOnlyHint: true
    • destructiveHint: false
    • idempotentHint: true
    • openWorldHint: false
Only reads 2Claude Code: allow
  • get_diagramFetch a published diagram's current Mermaid source by name or slug, and show it rendered.No findings

    Why it is in this group

    • The name "get_diagram" says "get": a word for reading.
    Description, as the server wrote it
    Fetch a published diagram's current Mermaid source by name or slug, and show it rendered. The returned source is stamped with the diagram's identity — keep the `line9:` frontmatter block when you edit it so that Line9 recognises the diagram when it is opened and published there instead of creating a new one. Requires Line9 sign-in. This connector cannot publish or save. To publish, the user opens the diagram in Line9 (the `open_url` link) and publishes there — not with the Line9 CLI.

    Annotations the server declares

    • readOnlyHint: true
    • destructiveHint: false
    • idempotentHint: true
    • openWorldHint: false
  • list_diagramsList the diagrams published in the user's Line9 workspace(s): name, visibility, version, last update and permalink.No findings

    Why it is in this group

    • The name "list_diagrams" says "list": a word for reading.
    Description, as the server wrote it
    List the diagrams published in the user's Line9 workspace(s): name, visibility, version, last update and permalink. Use it to find a diagram before `get_diagram`. Requires Line9 sign-in.

    Annotations the server declares

    • readOnlyHint: true
    • destructiveHint: false
    • idempotentHint: true
    • openWorldHint: false

This is not a safety rating, and no finding is not a safety guarantee. The groups and findings come from fixed checks of the tool definitions the server returned on the date shown, not from its code or what it does when called. How the checks work.

Install

Pinned to version 0.4.4. Values in angle brackets are yours to fill in.

claude mcp add --transport http diagrams https://mcp.line9.ai/mcp

Run in a terminal.

Claude Code permissions

Allow the reads, ask before a change, deny the deletes. Paste into .claude/settings.json.

.claude/settings.json
{
  "permissions": {
    "allow": [
      "mcp__diagrams__list_diagrams",
      "mcp__diagrams__get_diagram"
    ],
    "ask": [
      "mcp__diagrams__render_diagram"
    ],
    "deny": []
  }
}

Tools that only read are allowed, tools that change things ask first, tools that delete or cancel are denied. It assumes the server is installed as diagrams. Review it before you use it.