--- title: "MultiGroupPoster MCP Server for AI Assistants and Agents" description: "Connect Claude, ChatGPT or another AI assistant to MultiGroupPoster through its MCP server: the endpoint, OAuth sign-in, the tools, limits and errors." url: https://multiplegroupposter.com/docs/mcp/ source: MultiGroupPoster (https://multiplegroupposter.com) - Markdown version of the page above, for LLMs. --- # MCP server for AI assistants Updated October 28, 2026 ยท [Markdown version](https://multiplegroupposter.com/docs/mcp.md) Short answer MultiGroupPoster has a remote MCP server at https://mcp.multiplegroupposter.com/mcp. An AI assistant connects with OAuth, then a code from the extension and a number match link it to one person's extension. The assistant can list group lists, prepare posts and follow results. Posting itself happens in that person's Chrome, through the extension. ![The Connect an AI assistant window in MultiGroupPoster with the connector address and the Get my code button](https://multiplegroupposter.com/images/app/ai-help-dialog.webp) Help, then Connect an AI assistant, in the extension. ## Endpoint and sign-in Step-by-step for people, with the list of apps that support custom connectors: [AI assistants](https://multiplegroupposter.com/ai-assistant/). Machine-readable details: [/auth.md](https://multiplegroupposter.com/auth.md) and the server card at [/mcp/server-card](https://mcp.multiplegroupposter.com/mcp/server-card). It is listed in the official MCP Registry as `com.multiplegroupposter/multigroupposter` ([registry entry](https://registry.modelcontextprotocol.io/v0.1/servers/com.multiplegroupposter%2Fmultigroupposter/versions/latest)). | Item | Value | | --- | --- | | Endpoint | `https://mcp.multiplegroupposter.com/mcp` (Streamable HTTP, stateless) | | Auth | OAuth 2.1 with PKCE (S256). Dynamic client registration and client ID metadata documents are both supported. Scopes: `mgp`, `offline_access`. | | Discovery | [/.well-known/oauth-protected-resource](https://mcp.multiplegroupposter.com/.well-known/oauth-protected-resource) and [/.well-known/oauth-authorization-server](https://mcp.multiplegroupposter.com/.well-known/oauth-authorization-server). An unauthenticated call returns 401 with a `WWW-Authenticate` header that points to them. | | Linking | On the sign-in page the person types an 8-digit code from the extension (Help, then Connect an AI assistant, then Get my code; valid 20 minutes). The extension then asks them to pick the number the sign-in page shows. A wrong pick denies the request. | | Tokens | Refresh tokens last 180 days and renew with use. Disconnect in the extension removes the tokens and everything the connector kept. | | Test account | The sign-in page has "Try a demo account": two sample lists, nothing reaches Facebook, deleted after 3 days. Use it to test a client. | ## Tools There is also a prompt, `post_to_groups`, that walks through a post step by step. Every tool has read-only and destructive hints. | Tool | What it does | | --- | --- | | `get_started` | Setup state: whether the extension is online and signed in, the plan, group lists, recent posts and the suggested next step. Read-only. | | `list_group_lists` | The saved group lists (name, number of groups). Read-only. | | `create_post` | Creates a post for a group list: text (up to 5,000 characters), list name, up to 10 media ids, optional first comment (up to 1,000), method fast or safe, mode draft (default) or publish_now. publish_now needs `confirmed: true`, given only after the person said yes to a summary. | | `get_post_status` | Status of a post (queued, picked up, draft ready, posting, done, failed) with the result and link per group. Read-only. | | `list_recent_posts` | The last 10 posts made through the assistant. Check it before creating a post again after an unclear error. Read-only. | | `get_upload_link` | A one-time web page where the person uploads photos or videos (works on a phone, 24 hours). | | `list_uploaded_media` | Uploaded photos and videos with their media ids. Read-only. | | `add_media_from_url` | Downloads a photo or video from a public https link (up to 100 MB; JPG, PNG, GIF, WEBP, MP4, MOV). | | `open_post_composer` | Shows an in-chat card (MCP Apps) to add photos, edit the text and pick the list. It creates a draft. | ## How posting works - Draft is the default: the post waits in the extension until the person checks it and presses Publish. - Nothing is posted by the server. The extension in the person's Chrome picks the job up and posts it with their own Facebook session, method and pacing. If Chrome is closed, the job waits. - Publish now is counted against the free plan like any other post; drafts are not. - Uploaded media is kept 24 hours, posts 7 days. Disconnecting deletes them right away. ## Errors Tool errors come back as a normal result with `isError: true` and a JSON body `{"error": "...", "next_step": "..."}` (also in `structuredContent`). A failed post has a `code`: `free_plan_used_up`, `not_signed_in`, `busy`, `list_missing`, `list_empty`, `media_missing`, `storage`, `off`, `disconnected`, `not_posted`, `lost` or `error`, and `next_step` says what to tell the person. HTTP errors are JSON too: 401 `{"error":"invalid_token"}` with `WWW-Authenticate`, 404 `{"error":"not found"}`, 429 when a sign-in limit is hit. After an unclear error, do not call create_post again: call list_recent_posts first, so nothing is posted twice. ## On this website (WebMCP and the info API) The pages of multiplegroupposter.com also offer read-only WebMCP tools to an agent in the browser (where the browser supports WebMCP): `get_pricing`, `get_limits`, `search_docs`, `get_install_link` and `get_mcp_connection_info`. They only read facts from this site and send nothing anywhere. The same facts are available as JSON from [/api/v1/pricing/](https://multiplegroupposter.com/api/v1/pricing/), [/api/v1/limits/](https://multiplegroupposter.com/api/v1/limits/) and [/api/v1/docs/?q=](https://multiplegroupposter.com/api/v1/docs/?q=refund), described in [/openapi.json](https://multiplegroupposter.com/openapi.json). No key is needed. For AI agents: every docs page has a Markdown copy (add `.md` to the path), the whole section is indexed in [/docs/llms.txt](https://multiplegroupposter.com/docs/llms.txt) and [/docs.json](https://multiplegroupposter.com/docs.json), and the MCP server is described on [/docs/mcp/](https://multiplegroupposter.com/docs/mcp/). [Add to Chrome, free](https://chromewebstore.google.com/detail/multigroup-poster-%E2%80%93-faceb/bffigfjkllaipccbpnmckgfhmdmlgdda?utm_source=multiplegroupposter.com&utm_medium=page&utm_campaign=en-mcp)