mcp-mermaid MCP — Casos de uso, Instalar & Demo ao vivo

Name: mcp-mermaid MCP Server
Author: hustcc

Por que usar

Principais recursos

Full Mermaid syntax support — flowcharts, sequence, class, state, ER, gantt, etc.
Six output formats: base64, SVG text, Mermaid source, PNG file, SVG URL, PNG URL
Built-in syntax validation and multi-round self-correction
Configurable backgroundColor and theme
Docker deploy + SSE/Streamable HTTP transports

Demo ao vivo

Como fica na prática

mermaid.replay ▶ pronto

0/0

Instalar

Escolha seu cliente

~/Library/Application Support/Claude/claude_desktop_config.json · Windows: %APPDATA%\Claude\claude_desktop_config.json

{
  "mcpServers": {
    "mermaid": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-mermaid"
      ],
      "_inferred": true
    }
  }
}

Abra Claude Desktop → Settings → Developer → Edit Config. Reinicie após salvar.

~/.cursor/mcp.json · .cursor/mcp.json

{
  "mcpServers": {
    "mermaid": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-mermaid"
      ],
      "_inferred": true
    }
  }
}

Cursor usa o mesmo esquema mcpServers que o Claude Desktop. Config de projeto vence a global.

VS Code → Cline → MCP Servers → Edit

{
  "mcpServers": {
    "mermaid": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-mermaid"
      ],
      "_inferred": true
    }
  }
}

Clique no ícone MCP Servers na barra lateral do Cline, depois "Edit Configuration".

~/.codeium/windsurf/mcp_config.json

{
  "mcpServers": {
    "mermaid": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-mermaid"
      ],
      "_inferred": true
    }
  }
}

Mesmo formato do Claude Desktop. Reinicie o Windsurf para aplicar.

~/.continue/config.json

{
  "mcpServers": [
    {
      "name": "mermaid",
      "command": "npx",
      "args": [
        "-y",
        "mcp-mermaid"
      ]
    }
  ]
}

O Continue usa um array de objetos de servidor em vez de um map.

~/.config/zed/settings.json

{
  "context_servers": {
    "mermaid": {
      "command": {
        "path": "npx",
        "args": [
          "-y",
          "mcp-mermaid"
        ]
      }
    }
  }
}

Adicione em context_servers. Zed recarrega automaticamente ao salvar.

claude mcp add mermaid -- npx -y mcp-mermaid

Uma linha só. Verifique com claude mcp list. Remova com claude mcp remove.

Casos de uso

Usos do mundo real: mcp-mermaid

Generate a system architecture diagram from prose

👤 Engineers writing design docs ⏱ ~10 min beginner

Quando usar: You've described an architecture in a doc and want a diagram without leaving chat.

Pré-requisitos

mcp-mermaid installed — npx -y mcp-mermaid in your MCP client config

Fluxo

Describe the system

Here's my architecture: Cloudflare → API (Node) → Postgres + Redis → Worker (Go). Generate a Mermaid flowchart showing this.✓ Copiado

→ Valid Mermaid source rendered as SVG
Iterate on styling

Make Cloudflare blue, Postgres green, Redis red. Use dashed edges for async.✓ Copiado

→ Revised diagram
Save to file

Output as PNG file at ./docs/arch.png with white background.✓ Copiado

→ File on disk

Resultado: An architecture PNG you can drop into the design doc.

Armadilhas

Very complex diagrams hit Mermaid's layout limits — Break into multiple diagrams, or switch to subgraph grouping
Theme colors don't match your doc — Pass theme config explicitly rather than relying on defaults

Combine com: filesystem

Draft a sequence diagram in a bug report

👤 Engineers filing tricky race-condition bugs ⏱ ~5 min beginner

Quando usar: Prose description of who calls whom when is hard to read.

Fluxo

Describe the sequence

Client sends POST, API starts transaction, writes to DB, crashes before commit. Meanwhile a retry comes in from the client. Draw a sequence diagram.✓ Copiado

→ Clear sequence with parallel lifelines
Inline into issue

Give me the Mermaid source so I can paste into a GitHub issue (which renders Mermaid natively).✓ Copiado

→ Source ready to paste

Resultado: A bug report reviewers can grok in 10 seconds.

Combine com: github

Generate a project Gantt from a timeline

👤 Project leads who don't want to pay for gantt software for a one-off ⏱ ~5 min beginner

Quando usar: Ad-hoc timeline for a PRD or kickoff.

Fluxo

List phases

Phases: Discovery (2 weeks), Design (3 weeks), Implementation (6 weeks), QA (2 weeks overlap with impl last 2 weeks). Starting 2026-05-01. Make a gantt.✓ Copiado

→ Valid Gantt source
Output PNG

Save as PNG and also give me the URL I can embed in the PRD.✓ Copiado

→ PNG path + hosted URL

Resultado: A timeline graphic for your PRD in under a minute.

Combinações

Combine com outros MCPs para 10× de alavancagem

mermaid + filesystem

Save generated diagrams as versioned assets

Generate architecture diagram v2 as ./docs/arch-v2.png and update the reference in ./docs/README.md.✓ Copiado

mermaid + github

Put Mermaid source in a PR description — GitHub renders it natively

Draft a PR description explaining the data flow change, include a Mermaid sequence diagram inline.✓ Copiado

Ferramentas

O que este MCP expõe

Ferramenta	Entradas	Quando chamar	Custo
generate_mermaid	source: str (Mermaid DSL), output: base64\|svg\|mermaid\|file\|svgUrl\|pngUrl, theme?, backgroundColor?	Any diagram generation	free (local render) or 1 API call for hosted URLs
validate_mermaid	source: str	Before generate if you're unsure about syntax	free

Custo e limites

O que custa rodar

Cota de API: Local rendering is free; hosted URL output uses mermaid.ink which is free with reasonable use
Tokens por chamada: Small — diagram DSL is compact
Monetário: Free
Dica: Prefer 'mermaid' output for GitHub/docs that render natively; only go to PNG/SVG when rendering server-side is needed.

Segurança

Permissões, segredos, alcance

Armazenamento de credenciais: None

Saída de dados: Local render for base64/svg; mermaid.ink for hosted URLs

Hosted URLs (mermaid.ink) expose your diagram content — don't use for confidential system diagrams.
PNG rendering spawns a headless browser — make sure it's not exposed on the public internet.

Solução de problemas

Erros comuns e correções

Mermaid parse error

The LLM emitted invalid DSL. Validate via validate_mermaid first; mcp-mermaid also self-corrects on second pass.

Verificar: validate_mermaid on the source

PNG output fails in Docker

The image needs a headless browser; use the official Docker image which bundles it.

Verificar: docker run hustcc/mcp-mermaid

Diagram too big, gets cut off

Break into subgraphs or split into multiple diagrams.

Alternativas

mcp-mermaid vs. outros

Alternativa	Quando usar	Troca
PlantUML MCP	You prefer PlantUML's deeper UML surface	Requires Java runtime
antv-chart / mcp-server-chart	You need data charts more than diagrams	Different shape of output
Raw Mermaid via the web editor	You're not in a chat workflow	No MCP integration

Mais

Recursos

📖 Leia o README oficial no GitHub

🐙 Ver issues abertas

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