Mastodon MCP server: let Claude or any agent post to your Mastodon account

Set it up and post, step by step

1. Add PostWire's MCP server to your agent

   In Claude, open PostWire in the connector directory and press Connect. Anywhere else, add the remote server https://postwire.io/api/mcp (Streamable HTTP; OAuth sign-in or an API key) — in Claude Code: claude mcp add --transport http postwire https://postwire.io/api/mcp. Cursor, VS Code, Windsurf, Codex and Gemini CLI configs: MCP client configs.

2. Sign in with your email

   The first time the agent uses a PostWire tool, a sign-in window asks for your email and a 6-digit code; that also creates a free PostWire account if you have none. No password and no card. Agents that cannot do OAuth send an API key instead (dashboard → API & MCP → Copy key).

3. Create an access token in Mastodon

   On your Mastodon server, open Preferences → Development → New application, name it "PostWire", tick only write:statuses and write:media, save, and copy Your access token. With those two scopes the token can post and upload media; it cannot read your timeline or your messages. Deleting the application in Mastodon disconnects PostWire.

4. Connect Mastodon

   Ask "connect my Mastodon". create_connect_link gives you a one-hour link; choose Mastodon there and paste your server's address (https://mastodon.social, or your own instance) and the token. There is no sign-in screen. Before saving, PostWire asks your server whether the token is valid, so a wrong token is refused on that page with the fix, and it reads the server's post length limit to measure your posts against it.

5. Let PostWire write the post

   "Write a Mastodon post about our open-source release, and the LinkedIn post for it." generate_posts returns one draft per network and publishes nothing. Mastodon's draft stays within 500 characters, is community-first with no marketing-speak, and carries 2 to 4 hashtags in CamelCase (#OpenSource, which screen readers can read out). When the idea is too long for one post, or you ask for one, it comes back as a thread.

6. Publish, or schedule it

   After you approve, the agent calls post_to_social (or schedule_post with a run_at time, or "next_slot"). Images and videos go in media, each with its own alt; thread holds the posts after the first, and first_comment is a reply under the last one, a good place for the link:

   {
     "name": "post_to_social",
     "arguments": {
       "platforms": ["mastodon"],
       "per_platform": {
         "mastodon": {
           "text": "We open-sourced our scheduler today. It runs on one small server and a Postgres database. #OpenSource #SelfHosted",
           "thread": ["What took longest was daylight saving: a post set for 02:30 on the night the clocks change has to go out exactly once."],
           "first_comment": "Code and install notes: https://example.com/repo"
         }
       },
       "media": [
         { "url": "https://postwire.io/m/…/calendar.jpg", "alt": "A weekly calendar with six posts queued" }
       ]
     }
   }

7. Open the post, and see how it did

   The result carries the post's link on your server and, for a thread, the link of every post in it. get_post_status returns them again later, and get_post_performance ranks your Mastodon posts against your own median by favourites, boosts and replies, the numbers Mastodon reports. list_scheduled_posts shows what is queued and cancel_scheduled_post removes one before it goes out.

An image or a video from your phone or laptop gets there through create_upload_link: a 24-hour page where you pick the file (up to 100 MB on the free plan and 1 GB on paid plans), then get_uploaded_file returns its media_url. The same post from your own code: POST /api/post with {"platforms": ["mastodon"], "text": "…"} and your API key, or the PostWire node in n8n. Prefer to set it up by hand first? Open the dashboard, connect the account under Accounts and copy your key under API & MCP.