PostOnce MCP

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Hosted MCP Server

npx add-mcp 'https://postonce.app/api/mcp'

Installs into Claude Code, Codex, Cursor and more

Documentation

Any MCP client can use this hosted server. Paste the URL, finish sign-in in the browser, then ask for drafts. Clicks for a specific product live on ChatGPT, Grok, Cursor, and Claude.

Endpoint

Streamable HTTP at /api/mcp. Unauthenticated calls return 401 and expect a Bearer token. Sessions use Mcp-Session-Id.

https://postonce.app/api/mcp

OAuth

The same authorize, token, and dynamic client registration stack the hosted server already uses. Leave client id and secret empty unless your client already registered.

Authorize

https://postonce.app/oauth/authorize

Token

https://postonce.app/api/oauth/token

Revoke

https://postonce.app/api/oauth/revoke

Scopes

postonce:read · postonce:write

Discovery

/.well-known/oauth-protected-resource
/.well-known/oauth-authorization-server

Bearer

Send the access token as Authorization: Bearer <token>. That is the header the 401 challenge expects.

API keys from Settings → More → API access remain a fallback for Claude Code and scripts that cannot open a browser. Those keys never go in the chat. Revoke bot access under Settings → More → Connected bots.

Media from a public URL

Hosted MCP can pull a public image or video URL onto the PostOnce CDN, then pass that URL in mediaUrls on a draft. Chat-dropped files still cannot; the client has to give a fetchable https link (your CDN, a Dropbox/Drive direct file, or another already-hosted asset). Local Claude Code can also upload a file path.

How to start in a generic client

  1. Add https://postonce.app/api/mcp as the remote MCP server.
  2. Sign in if asked. Hit Allow.
  3. Tell the bot which Instagram, Facebook page, TikTok, LinkedIn, or Pinterest you already run. Connect those at /accounts. Don't create new brand pages unless you have none.
  4. Drafts first. Nothing goes live until you say yes.

Grok Bot referral URL

grok.com uses https://postonce.app/api/mcp. The Grok Bot plugin at grokbot.dev/plugins/postonce still uses this referral URL. Clicks live on the Grok setup page.

https://postonce.app/api/mcp?ref=grokbot

Don't paste API keys into the chat.

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