Add the thirds.ai MCP server to Cursor

You add the thirds.ai MCP server to Cursor with one entry in mcp.json, and then you sign in on a thirds.ai page or with an API key. With thirds.ai, you save a design once, such as an invoice, a report, a certificate, or a social post, with your logo, colours, and fonts. Then you type in new details and get a finished PDF or image. Once Cursor has the server, you can ask Cursor Agent for those files while you code, so you don't have to leave your editor or lay out each one by hand. Each successful PDF or image costs one credit, and a verified account gets 50 free credits each month.

See the Cursor image examples for designs and prompts to try after setup. If you also build apps in Replit, the Replit MCP setup connects Replit Agent to the same saved designs. For apps you build in Lovable, the Lovable MCP setup adds them to Lovable chat.

Make it without code

You can make the same branded files in the thirds.ai editor without Cursor or any code. It takes three steps, and you need a free thirds.ai account.

1. Open the Changelog card template and click Use this template. Sign in and verify your account first if you need to.
2. Open the Data tab and type your product name, the version, the headline, and each change. Click Preview with data above the canvas to see the card. The preview is free.
3. Click Export, then Save and export PNG, and click Download image.

When you want Cursor Agent to make the next card for each release, add the thirds.ai MCP server to Cursor.

How do I add the thirds.ai MCP server to Cursor?

You add the thirds.ai MCP server to Cursor with one server entry in mcp.json, and then Cursor signs in with only the URL or with an API key. You need a thirds.ai account and Cursor on your computer. The Cursor MCP guide (checked 27 September 2026) says Cursor supports OAuth for servers that need it, and thirds.ai uses OAuth when you give only the URL.

Sign in with only the URL

1. Create ~/.cursor/mcp.json to use thirds.ai in all your projects, or .cursor/mcp.json inside one project. Add this entry:

{
  "mcpServers": {
    "thirds": {
      "url": "https://thirds.ai/mcp"
    }
  }
}

2. When the thirds.ai page opens, sign in if you need to and click Allow. In the Cursor CLI, run agent mcp login thirds to start the sign-in. The Cursor CLI MCP guide lists this command (checked 27 September 2026).

This connection gets every thirds.ai tool except the two AI image tools. Sign in with an API key when you need those. To stop the connection, open your thirds.ai Settings, find the app under Connected apps, and click Disconnect. The app loses access right away.

Sign in with an API key

1. Create an API key on the API keys page.
2. Set THIRDS_API_KEY in the environment that starts Cursor.
3. Add this entry to ~/.cursor/mcp.json or .cursor/mcp.json:

{
  "mcpServers": {
    "thirds": {
      "url": "https://thirds.ai/mcp",
      "headers": {
        "Authorization": "Bearer ${env:THIRDS_API_KEY}"
      }
    }
  }
}

The same Cursor guide says Cursor supports Streamable HTTP servers, request headers, and ${env:NAME} values in mcp.json. Cursor reads your key from the environment when it connects, so the key stays out of the file and out of source control.

Add the thirds.ai plugin to Cursor

The thirds.ai plugin gives Cursor the thirds.ai server and nine task guides, such as filling a saved design or making one file for each row of a list. The plugin lives in the public thirds.ai skills repository. You add it as a local plugin in three steps. The Cursor plugin guide says Cursor loads a plugin from a folder in ~/.cursor/plugins/local (checked 30 September 2026). You need Git and a thirds.ai account.

1. Copy the plugin into your Cursor plugins folder:

git clone https://github.com/thirdsai/skills ~/.cursor/plugins/local/thirds-ai

2. Restart Cursor, or run Developer: Reload Window.
3. Open Customize and check that the thirds.ai skills and the thirds server are there. When the thirds.ai page opens, sign in if you need to and click Allow.

The plugin signs in with only the URL, so it doesn't get the two AI image tools. To update the plugin, run git -C ~/.cursor/plugins/local/thirds-ai pull and reload the window. If you already added thirds to mcp.json, remove one of the two, so Cursor doesn't run the server twice.

What Cursor can and can't do with thirds.ai

Cursor Agent can make PDFs and images from gallery templates and your saved designs, in your own logo, colours, and fonts. Cursor works only with the designs, brand kits, and files in your own thirds.ai account, and it spends that account's credits. Ask Cursor Agent to show the cost before each paid step.

Cursor Agent can find your designs and brand kits, make a PDF, PNG, JPEG, or WebP, preview a design for free, save a brand kit, and turn HTML, a description, or a picture into a design you can edit. It can also make one file for each row of a list, fit an image design to new sizes, and export carousel slides. With an API key, it can make AI pictures too.

Cursor Agent can't edit a PDF or Word file you already have. It can't make videos, post to social networks, or send email through thirds.ai. With a URL sign-in or the plugin, it can't make AI pictures.

Check that Cursor sees the thirds.ai tools

You check the thirds.ai connection in Cursor from the Customize page or from the Cursor CLI. The Cursor CLI MCP guide says both use the same configuration, so a server that works in one works in the other.

Open Customize in the Cursor sidebar, find thirds, and turn it on. In the Cursor CLI, run agent mcp list to see the server, and agent mcp list-tools thirds to see its tools.

If thirds doesn't connect, open the Output panel and choose MCP Logs. A missing key or a typo in the Authorization line shows up there.

Make your first file from Cursor

Your first file from Cursor starts with a plain request to Cursor Agent. Ask it to list the thirds.ai tools, then ask for one file, such as "Make a changelog card for version 2.5 from my Changelog card template." Cursor's MCP guide says Cursor asks you to approve each tool call by default, so you see what the agent sends before it runs.

Read the main MCP guide before your first paid call. It explains credit approval, safe retries, and status checks. If you run your terminal in Warp, you can add the thirds.ai MCP server to Warp with a similar JSON entry.

Privacy, terms, and help

When you connect Cursor, it can make files and read and change your designs and brand kits with your thirds.ai account and credits. Our privacy policy says what we keep about each connected app and for how long, and the Terms of Service cover your use of thirds.ai through Cursor. For help with the server, the plugin, or a failed file, contact support.

FAQ

Why does Cursor not see the environment variable?

Start Cursor from an environment that has THIRDS_API_KEY, or add the variable to the system environment used by the app. Restart Cursor after you change it.

Which configuration file should I use?

Use ~/.cursor/mcp.json for your own global setup. Use .cursor/mcp.json to share the server definition with a project. Each user still needs a private key. If you also code in Google Antigravity, add the thirds.ai MCP server to Antigravity with serverUrl in place of url. If part of your team uses VS Code, add the thirds.ai MCP server to VS Code too. VS Code uses its own mcp.json format and asks for the key when the server starts.

Can I put the key in an envFile?

No. Cursor's MCP guide says envFile works only for local command servers, and thirds.ai is a remote server. Set THIRDS_API_KEY in your shell profile or system environment instead.

Does connecting spend credits?

No. Connecting and listing tools don't spend credits. AI template work and successful files can. Ask your agent to show the action and the cost before it starts paid work.