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Mermaid Chart
Render Mermaid diagrams inside a Claude conversation.
Opens Agent Studio, where connecting is one click. The connector URL below works in any MCP client.
Paste it into any MCP client. Setup docs
What the Mermaid Chart connector does
The Mermaid Chart MCP server turns Mermaid diagram code into a rendered diagram inside a Claude conversation. One read-only tool validates the syntax and returns SVG, PNG and a live-edit link. No sign-in is required, and the connector cannot touch your Mermaid Chart account — the interactive preview you see is drawn by a widget in the client.
Verified connector
Listed by Anthropic as a partner connector in its Connectors Directory.
Connection checked by Agentman on .
Anthropic states this reflects the level of review a connector received, not a security audit.
Mermaid Chart tools (1)
- validate_and_render_mermaid_diagramRead-only
Use this tool to output a Mermaid diagram: - The tool will validate the diagram syntax and render it to a UI widget. - The widget will contain the diagram code, a "Copy Code" button, and a rendered diagram. - If the diagram is invalid, the widget will give user a link to repair the diagram in Mermaid.
Read from the server on 2026-08-18, including each tool's own safety annotations.
Limits
- It renders; it does not manage. One read-only tool. No save, list, update, delete or share call exists, and the connector reaches no part of your Mermaid Chart account.
- The interactivity is the client's, not the server's. Preview, zoom and iterate happen inside the widget. Without MCP Apps support you get the returned SVG, PNG and link as content.
- Two input fields, and the schema is closed.
diagramCodeand an optionaltitle, withadditionalProperties: false. No theme, size, format, project or document parameter. - No repair in v1. An invalid diagram produces an error field and a link to Mermaid Live. Automatic AI repair is documented on the v2 server, not this one.
- Declared for Claude only. Anthropic's directory lists
works_with: ["claude"]— no Claude Code, no Claude Desktop, no API. - No prompts. The capability is not declared;
prompts/listreturns-32601. - The widget phones home. Its declared CSP permits connections to
*.mixpanel.com, so usage telemetry reaches Mermaid's analytics provider from the rendering surface. - No published rate limit. Neither the documentation nor the handshake states a request ceiling, so we make no claim about one.
- No published price for this endpoint. Mermaid Chart is a paid product with a pricing page, but Mermaid publishes no cost, quota or diagram limit for this connector. We do not infer one.
- The directory's documentation link points at a different server. It resolves to Mermaid's general MCP Server page, which documents nine tools at
https://mcp.mermaid.ai/mcp. Read the Claude MCP App page instead for this connector.
Frequently asked questions
Does the Mermaid Chart connector need a Mermaid Chart account?
No. We opened an anonymous handshake on 2026-08-18 and the server returned its tool definition with no credential and no authentication challenge. The connector renders diagrams your assistant writes; it never reaches your Mermaid Chart account, your saved diagrams or your projects. Account features live on separate Mermaid servers that this endpoint does not expose.
Can Claude save a diagram to my Mermaid Chart account through this connector?
No. The single tool is annotated read-only and non-destructive, and its schema accepts only diagram code and an optional title. There is no save, update, list or delete call anywhere in the surface. Mermaid documents saving and listing on two other servers, each at a different URL you would have to add yourself.
Where does the interactive preview and zoom actually happen?
In your client, not on the server. The server validates the code and returns rendered SVG and PNG plus a live-edit link, then points the client at a widget resource. Claude fetches that widget and draws the diagram, the Copy Code button and the repair link. A client without MCP Apps support shows the returned data as plain content.
What happens when the Mermaid syntax is invalid?
The tool reports the failure rather than throwing it away. Its output carries an error or validationError field, and Mermaid's documentation says the widget then offers a link to repair the diagram in Mermaid Live. The v1 connector does not repair syntax itself; the repair is a link you follow, not a tool call.
Which Mermaid diagram types does the connector support?
Every type the Mermaid library parses, because the server validates the code rather than a fixed list. Mermaid's own example prompts name flowcharts, sequence diagrams, class diagrams and state diagrams, and the tool returns a diagramType field naming what it detected. The connector's limit is Mermaid syntax itself, not a shorter allowlist.
Is the Mermaid Chart MCP connector free to use?
Mermaid publishes no price for this endpoint, and we make no claim about one. The connector needs no account, so no plan gate applies at the point of rendering. Mermaid Chart is a paid product with a published pricing page, and the account features documented on its other MCP servers plainly require an account; check mermaid.ai/web/pricing for what a plan covers.
Does the connector work in ChatGPT or Claude Code?
Anthropic's directory declares this connector works with Claude only — not Claude Code, not Claude Desktop, not the API. That is narrower than most entries in this catalogue. The endpoint is a standard streamable-HTTP MCP server and answered our anonymous handshake, but the interactive widget depends on MCP Apps support in the client.
Sources
- Mermaid Claude MCP App documentation (fetched 2026-08-18). This is the page that documents the connector at the directory-listed endpoint. The directory's own
documentationfield points elsewhere; see below. · retrieved 2026-08-18 - Mermaid Claude MCP App v2 documentation (fetched 2026-08-18). Documents a separate endpoint,
https://chatgpt.mermaid.ai/anthropic/v2/mcp, cited here only for the v2 section. · retrieved 2026-08-18 - Mermaid MCP Server documentation (fetched 2026-08-18). The directory publishes
https://docs.mermaidchart.com/ai/mcp-server, which redirects to this URL; the resolved URL is the one cited.docs.mermaidchart.com/robots.txtis a blanketDisallow: /carrying the comment that all content has moved tomermaid.ai, andmermaid.ai/robots.txtdisallows only/app/, so every page cited here is permitted at its resolved location. · retrieved 2026-08-18 - Live MCP handshake against
https://chatgpt.mermaid.ai/anthropic/mcp—initialize,tools/list,resources/list,prompts/list,resources/templates/listandresources/readon the widget URI, 2026-08-18. Anonymous, read-only; no tool was called. · retrieved 2026-08-18 - Anthropic Connectors Directory entry (snapshot 2026-08-16). The URL returns 403 to our client; the entry data comes from the committed directory snapshot. · retrieved 2026-08-16
- Mermaid Chart privacy policy (fetched 2026-08-18). The directory lists
https://www.mermaidchart.com/privacy-policy, which redirects to this URL. · retrieved 2026-08-18 - Mermaid Chart issue tracker (checked 2026-08-18). Named by Mermaid's documentation as the place to report connector problems. · retrieved 2026-08-18
- Mermaid Chart pricing — . Linked, not summarised: Mermaid publishes no price for this connector and we state none.
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