How to Use posterly with Cursor: MCP in the IDE to First Approved Schedule

You already live in the editor. You do not want to context-switch into a social dashboard to queue a launch post. That is what posterly's MCP server is for inside Cursor.

Cursor is the agent layer (and the tool-approval prompt). posterly is the publish layer: 18 networks, the queue, analytics. Cursor does not post until you approve the tool and you confirm the specific post with create_post confirm: true.

This is a new-user walkthrough, from mcp.json to the first approved schedule. The long encyclopaedia is the Cursor guide. Fields sit on poster.ly/cursor.

Two layers, one repo

• Cursor Desktop and the local CLI can launch npx -y posterly-mcp-server@latest as stdio. That path can read a real file_path on disk.
• Cursor Cloud Agents, Automations, and the Slack bot cannot see your laptop process. They need url plus an Authorization header pointing at https://www.poster.ly/api/mcp.
• posterly holds accounts, media, and the queue. Buy Starter + API in one checkout ($10 a month). Agency API is $29 a month on Agency. See pricing.

A stray comma in mcp.json disables every server in that file. Validate the JSON before you blame the API key.

1. Put the server in mcp.json

Project file: .cursor/mcp.json. Global file: ~/.cursor/mcp.json. Settings UI: MCP, then Add new global MCP server.

Local stdio (Desktop):

{
  "mcpServers": {
    "posterly": {
      "command": "npx",
      "args": ["-y", "posterly-mcp-server@latest"],
      "env": {
        "POSTERLY_API_KEY": "pst_live_your_key_here"
      }
    }
  }
}

Cloud Agents:

{
  "mcpServers": {
    "posterly": {
      "url": "https://www.poster.ly/api/mcp",
      "headers": {
        "Authorization": "Bearer pst_live_your_key_here"
      }
    }
  }
}

If you do not have a key yet, you can still ask Cursor to run agent signup through the public flow, then paste pst_live_... into the file.

You: Set up posterly as my social scheduling agent. I do not have an account. Do not post anything.

Cursor: I can start posterly's agent signup. Confirm the email. You will pay and set a password in the browser. I will not take the card.

2. Agent-led signup (you still pay in the browser)

Same contract as every other client:

1. start_signup with Starter and api_addon=true.
2. You open checkout and pay.
3. get_signup_session until the key exists.
4. You paste the key into mcp.json. Cursor does not invent it.

No social passwords in the editor chat.

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3. whoami, then stop if it fails

Cursor asks before write tools unless you allowlist the server. Keep the prompt on until you trust the setup.

You: Run whoami. Do not post anything.

Cursor: Authenticated. Workspace and scopes look fine. No social accounts yet.

If this fails, the usual causes are a JSON typo, Node missing for npx, Cloud Agents still pointed at stdio, or the add-on off.

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4. First connect session (OAuth in the browser)

create_connect_session, you open connect_url, provider consent, get_connect_session until connected. 30 minutes. Manual networks wait for a credential in posterly, not in the agent transcript.

5. Media is where Cursor is actually better

Chat attachments in Cursor still never become MCP arguments. The paperclip is not an upload.

On Desktop stdio, give a real path:

You: upload_media with file_path /Users/me/Desktop/launch.mp4 then validate_post for LinkedIn.

On Cloud Agents that can HTTP PUT:

You: create_signed_upload for launch.mp4, PUT the bytes to upload_url, then validate_post with public_url.

If the Cloud Agent cannot PUT (some hosted runtimes cannot), use create_media_drop, open https://www.poster.ly/drop/<token>, then list_media. Same drop page ChatGPT uses.

Do not send a 500MB R2 URL to create_post. That fetch dies with remote_media_too_large. See Solving the 4MB MCP limit.

6. Draft, validate, then say send

1. Draft in the thread.
2. validate_post.
3. Preview account, caption, time, media.
4. You confirm that exact post.
5. create_post with confirm: true.

You: Draft a LinkedIn post for Thursday 10:00 UK time. Validate it. Do not create it.

Cursor: validate_post passed. No row exists yet.

You: Schedule it.

Cursor: Scheduled. View in Posterly: [dashboard link]

Batch with create_posts_batch. Voice with get_learned_voice. Analytics with get_account_analytics.

Allowlisting the MCP server skips Cursor's tool prompt. It does not skip posterly's confirm: true.

7. Where this usually breaks

• Cloud Agents + stdio. The VM has no npx process on your Mac. Use the hosted URL.
• Stray comma in mcp.json. Every MCP server in that file goes dark.
• Paperclip. Still not MCP. Use file_path, signed upload, or create_media_drop.
• Skipped confirm. Tool refuses.
• Stale OAuth. New session.

Start in Settings, MCP

Paste stdio or the hosted URL from the MCP setup guide, walk agent signup if you are new, then approve one validated post. The short Cursor setup page has both JSON blocks.

You keep the editor. posterly keeps the queue. Nothing publishes until you say send.