iflow-mcp_andrewginns-mermaid-mcp-server

# Mermaid MCP Server A Model Context Protocol (MCP) server for validating Mermaid diagrams. Implements a minimal Python wrapper over https://github.com/mermaid-js/mermaid-cli for simpler out of the box use. ## Overview Python MCP server for validating Mermaid diagrams and (optionally) rendering them as PNG images. It uses the Mermaid CLI tool to perform the validation and rendering. The server provides LLMs with structured validation results including: - **Boolean validation status** (`is_valid: true/false`) indicating whether the Mermaid diagram syntax is correct - **Detailed error messages** explaining exactly what went wrong if validation fails (e.g., syntax errors, unsupported diagram types, malformed nodes) - **Optional base64-encoded PNG images** of successfully rendered diagrams for visual verification This enables LLMs to programmatically validate Mermaid diagram syntax, understand specific errors to provide helpful corrections, and optionally receive visual confirmation of the rendered output. Also provides a simple Pydantic-AI MCP Client to invoke the MCP server using a Gemini model for testing. ## Prerequisites **Important**: This MCP server requires Node.js to be installed on your system, even if you're only using the server component (not the client). The server internally calls `npx @mermaid-js/mermaid-cli` as a subprocess to perform diagram validation and rendering. ### Required Dependencies - **Node.js** with npm (required for all usage) - **Mermaid CLI**: Install with `npm install -g @mermaid-js/mermaid-cli` - **Python** with uv (for running the MCP server) ### Quick Dependency Setup ```bash # Install Mermaid CLI globally npm install -g @mermaid-js/mermaid-cli # Verify installation npx @mermaid-js/mermaid-cli --version ``` ## Quickstart To use this server with an MCP client (like Claude Desktop), add the following configuration to your MCP settings: **Note**: Make sure you have Node.js and Mermaid CLI installed (see Prerequisites a…