MCP Media Forge

MCP server that generates diagrams, charts, HTML pages, and slide decks from text DSLs -- designed for AI coding agents to embed into Markdown.

LLM agents call tools like render_mermaid, render_html_page, or render_slides with text input, and get back file paths to assets ready to embed in docs.

Output Gallery

Mermaid Flowchart

Mermaid Sequence Diagram

D2 Architecture Diagram

Graphviz Dependency Graph

Vega-Lite Bar Chart

Tools

Diagram & Chart Renderers (Docker)

| Tool | Input | Formats | Use Case | |------|-------|---------|----------| | render_mermaid | Mermaid code | SVG, PNG | Flowcharts, sequence, ER, state, Gantt, git graphs | | render_d2 | D2 code | SVG, PNG | Architecture diagrams with containers and icons | | render_graphviz | DOT code | SVG, PNG | Dependency graphs, network diagrams | | render_chart | Vega-Lite JSON | SVG, PNG | Bar, line, scatter, area, heatmap charts |

HTML Generators (No Docker)

| Tool | Input | Output | Use Case | |------|-------|--------|----------| | render_html_page | HTML body + theme | Self-contained HTML | Technical docs, reports, dashboards | | render_slides | JSON slide array + theme | HTML slide deck | Presentations, status updates, walkthroughs |

Utilities

| Tool | Description | |------|-------------| | get_tool_guide | Usage examples, anti-patterns, complexity limits per tool | | list_assets | List all generated files in the output directory |

Quick Start

1. Start the rendering container (for diagram tools)

cd docker
docker compose up -d

HTML page and slide tools work without Docker.

2. Install the MCP server

Option A -- npx (no install)

npx mcp-media-forge

Option B -- Clone and build

git clone https://github.com/PavelGuzenfeld/mcp-media-forge.git
cd mcp-media-forge
npm install
npm run build

3. Register with your MCP client

Any MCP-compatible client (Claude Code, Cursor, VS Code + Copilot, Cline, etc.) can use this server. The standard config:

{
  "mcpServers": {
    "media-forge": {
      "command": "node",
      "args": ["/path/to/mcp-media-forge/dist/index.js"],
      "env": {
        "PROJECT_ROOT": "/path/to/your/project"
      }
    }
  }
}

Where to add this depends on your client:

• Claude Code: ~/.claude/settings.json
• Cursor: MCP settings panel
• VS Code (Copilot): .vscode/mcp.json
• Cline: MCP server configuration

4. Use it

Ask your AI assistant to generate diagrams, pages, or presentations:

"Create a sequence diagram showing the OAuth2 flow and embed it in the README"

"Generate an HTML page summarizing the API architecture with KPI cards"

"Make a slide deck with our Q1 metrics and architecture overview"

The agent calls the appropriate tool, gets back a file path, and embeds it in your markdown.

How It Works

AI Agent (any MCP client)
    |
    | MCP Protocol (JSON-RPC over stdio)
    v
MCP Media Forge (Node.js on host)
    |
    |--- Diagrams: docker exec (sandboxed, no network)
    |       |
    |       v
    |   Rendering Container
    |     ├── mmdc       (Mermaid CLI + Chromium)
    |     ├── d2         (D2 diagrams)
    |     ├── dot/neato  (Graphviz)
    |     └── vl2svg     (Vega-Lite via vl-convert)
    |
    |--- HTML/Slides: template engine (no Docker)
    |       |
    |       v
    |   CSS Design System (4 themes, depth tiers, components)
    |
    v
docs/generated/
  mermaid-a1b2c3.svg
  d2-7f8e9a.svg
  html_page-d4e5f6.html
  slides-8b9c0d.html

Key design decisions:

• Text in, file path out -- returns relative paths, never base64 blobs
• Content-hash naming -- same input = same file = free caching + git-friendly
• SVG preferred -- vector format, small files, diffs cleanly in git
• Docker-contained -- diagram renderers run in a sandboxed container with network_mode: none
• Self-contained HTML -- pages and slides have zero external dependencies (inline CSS/JS)
• Input pre-validation -- catches common mistakes before Docker round-trips
• Structured errors -- error responses include error_type, error_message, and suggestion to enable LLM self-correction

Tool Reference

get_tool_guide

Get usage guide for any tool before rendering. Returns examples, anti-patterns to avoid, complexity limits, and tips.

{ "tool_name": "mermaid" }

Available guides: mermaid, d2, graphviz, vegalite, html_page, slides, or all for a summary.

render_mermaid

{
  "code": "flowchart TD\n    A[Start] --> B{Decision}\n    B -->|Yes| C[Done]",
  "format": "svg",
  "theme": "default"
}

| Parameter | Type | Default | Description | |-----------|------|---------|-------------| | code | string | required | Mermaid diagram code (must start with diagram type) | | format | svg | png | svg | Output format | | theme | default | dark | forest | neutral | default | Mermaid theme |

Pre-validation catches: missing diagram type, semicolons, HTML in labels, >25 nodes.

render_d2

{
  "code": "client -> server -> database",
  "format": "svg",
  "layout": "dagre"
}

| Parameter | Type | Default | Description | |-----------|------|---------|-------------| | code | string | required | D2 diagram code | | format | svg | png | svg | Output format | | theme | number | -- | Theme ID (0=default, 1=neutral-grey, 3=terminal) | | layout | dagre | elk | tala | dagre | Layout engine |

Pre-validation catches: Mermaid/D2 syntax confusion, unbalanced braces, >3 nesting depth.

render_graphviz

{
  "dot_source": "digraph G { A -> B -> C }",
  "engine": "dot",
  "format": "svg"
}

| Parameter | Type | Default | Description | |-----------|------|---------|-------------| | dot_source | string | required | Graphviz DOT source code | | engine | dot | neato | fdp | sfdp | twopi | circo | dot | Layout engine | | format | svg | png | svg | Output format |

Pre-validation catches: missing graph wrapper, -> in undirected graphs, unbalanced braces.

render_chart

{
  "spec_json": "{\"$schema\":\"https://vega.github.io/schema/vega-lite/v5.json\",\"data\":{\"values\":[{\"x\":1,\"y\":10}]},\"mark\":\"bar\",\"encoding\":{\"x\":{\"field\":\"x\"},\"y\":{\"field\":\"y\"}}}",
  "format": "svg"
}

| Parameter | Type | Default | Description | |-----------|------|---------|-------------| | spec_json | string | required | Vega-Lite JSON specification | | format | svg | png | svg | Output format | | scale | number | 1 | Scale factor for PNG output |

Pre-validation catches: invalid JSON, missing $schema/data/mark, >500 inline data rows.

render_html_page

Generates a self-contained themed HTML page. No Docker required.

{
  "title": "System Overview",
  "body_html": "<section id=\"metrics\"><h2>Metrics</h2><div class=\"mf-grid mf-grid-3\">...</div></section>",
  "theme": "swiss",
  "description": "Q1 architecture overview",
  "nav_sections": ["Metrics", "Architecture", "Roadmap"]
}

| Parameter | Type | Default | Description | |-----------|------|---------|-------------| | title | string | required | Page title | | body_html | string | required | HTML body content (inner content only, no <html>/<head>/<body>) | | theme | swiss | midnight | warm | terminal | swiss | Visual theme | | description | string | -- | Page description (meta tag + header) | | nav_sections | string[] | -- | Section names for floating IntersectionObserver navigation |

Design system CSS classes:

| Class | Purpose | |-------|---------| | mf-hero | Primary highlight section (large shadow) | | mf-elevated | Secondary highlight (medium shadow) | | mf-card | Bordered content card | | mf-recessed | De-emphasized content | | mf-grid mf-grid-2 | Responsive 2-column grid | | mf-grid mf-grid-3 | Responsive 3-column grid | | mf-split | Two equal columns | | mf-kpi + mf-kpi-value + mf-kpi-label | Key metric display | | mf-badge-success/warning/error/info | Status badges |

Themes:

| Theme | Style | Best for | |-------|-------|----------| | swiss | White, geometric, blue accent | Technical docs | | midnight | Deep navy, serif, gold accent | Presentations | | warm | Cream paper, bold sans, terracotta | Reports | | terminal | Dark, monospace, cyan accent | Developer content |

render_slides

Generates a self-contained HTML slide deck with keyboard/touch navigation. No Docker required.

{
  "title": "Q1 Review",
  "slides": "[{\"title\":\"Q1 Review\",\"content\":\"Engineering update\",\"type\":\"title\"},{\"title\":\"Metrics\",\"content\":\"<ul><li>99.9% uptime</li></ul>\",\"type\":\"content\"}]",
  "theme": "midnight",
  "author": "Engineering Team"
}

| Parameter | Type | Default | Description | |-----------|------|---------|-------------| | title | string | required | Presentation title | | slides | string | required | JSON array of slide objects | | theme | swiss | midnight | warm | terminal | swiss | Visual theme | | author | string | -- | Author (shown on title slide) |

Slide types:

| Type | Layout | Best for | |------|--------|----------| | title | Centered large text + subtitle | Opening/closing slides | | section | Centered heading + description | Topic dividers | | content | Heading + body (bullets, text) | Most content | | split | Heading + two columns | Before/after, comparisons | | code | Heading + code block | Code walkthroughs | | quote | Large blockquote + attribution | Testimonials, key quotes | | kpi | Heading + auto-grid metrics | Dashboards, stats | | image | Heading + centered image | Screenshots, diagrams |

Navigation: Arrow keys, Space, PageUp/PageDown, Home/End. Touch: swipe left/right. Click dots to jump.

list_assets

{ "directory": "" }

Returns a JSON array of all generated files with name, path, size, and modification time.

Error Handling

All tools return structured errors that help LLMs self-correct:

{
  "status": "error",
  "error_type": "syntax_error",
  "error_message": "First line must declare diagram type. Got: \"A --> B\"",
  "suggestion": "Start with: flowchart TD, sequenceDiagram, erDiagram, ... See https://mermaid.js.org/syntax/"
}

Error types: syntax_error, rendering_error, dependency_missing.

Pre-validation catches common LLM mistakes before hitting the renderer:

• Mermaid: missing diagram type, semicolons, HTML tags, legacy graph syntax
• D2: Mermaid syntax confusion (-->, subgraph), unbalanced braces
• Graphviz: missing digraph/graph wrapper, -> in undirected graphs
• Vega-Lite: invalid JSON, missing required fields, oversized inline data

Environment Variables

| Variable | Default | Description | |----------|---------|-------------| | PROJECT_ROOT | cwd() | Project root for output path resolution | | OUTPUT_DIR | docs/generated | Output directory relative to PROJECT_ROOT | | MEDIA_FORGE_CONTAINER | media-forge-renderer | Docker container name |

Development

npm install
npm run build          # Build with tsup
npm run dev            # Watch mode
npm test               # Run all tests (95 total)
npm run test:unit      # Unit tests only (no Docker needed)
npm run test:component # Integration tests (Docker tools need container)
npm run lint           # Type-check with tsc

Running integration tests

cd docker && docker compose up -d   # Start renderer (diagram tools only)
cd .. && npm run test:component     # All integration tests

HTML page and slide integration tests run without Docker.

Examples

See examples/ for sample input files:

| File | Tool | Description | |------|------|-------------| | mermaid/flowchart.mmd | render_mermaid | Decision flowchart | | mermaid/sequence.mmd | render_mermaid | Client-server sequence | | d2/architecture.d2 | render_d2 | Backend architecture with containers | | graphviz/dependencies.dot | render_graphviz | npm dependency graph | | vegalite/bar-chart.json | render_chart | Tool performance comparison |

See examples/README.md for MCP tool call examples and expected responses.

License

MIT