The Mastodon MCP server
Let Claude, ChatGPT, Cursor or any MCP client schedule posts and threads on any Mastodon instance, from mastodon.social to your own server.
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Claude scheduling to Mastodon through Postbase
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PostbaseHow posting to Mastodon works
- Length
- 500 characters per post, the default on most instances.
- Instances
- Works with any instance you've connected: mastodon.social, fosstodon.org or your own.
- Threads
- Send a thread array and each post is published as a reply to the one before.
- Hashtags
- Posted as written, so hashtags work the way they do when you type them.
Checked before it's queued
Problems come back to the agent when it calls the tool, not hours later when the post is due.
- Too long
- A scheduled post over 500 characters is refused when the agent calls the tool, with the reason.
- In the past
- A time in the past is refused rather than posted straight away.
- Drafts
- Leave out the time and the post is saved as a draft for you to check first.
The tools
The same four tools on every network.
list_channelsRead onlyThe accounts connected to the workspace: id, network, handle and status. The agent calls it first to get channel ids.
No arguments.
create_postWritesSaves a draft, or schedules a post or a thread, on one or more channels. The post lands on your Postbase calendar and publishes through each network's official API.
body or thread, channel_ids, and scheduled_at (ISO 8601 with an offset) or schedule_in_minutes. Leave both times out to save a draft.
list_scheduledRead onlyPosts in the workspace with their text, time and channels. Scheduled posts by default, or drafts, published or failed ones.
status (optional): scheduled, draft, published or failed.
cancel_postWritesCancels a scheduled post before it goes out. It goes back to being a draft, so nothing is deleted.
post_id, from list_scheduled.
Frequently asked questions
Does it work with my instance?
Yes. Connect your Mastodon account to Postbase with your instance URL and approve it on your server, and the agent can post to it like any other channel.
Do I have to run the MCP server myself?
No. The server is hosted at mcp.postbase.so. If you'd rather self-host everything, Postbase and its MCP package are open source.
Can it boost or reply to other posts?
No. It schedules your own posts and threads only. There are no tools for boosts, favourites, replies to others or DMs.
Related
- Claude + Mastodon
Set up Claude to post to Mastodon.
- Claude Code + Mastodon
Set up Claude Code to post to Mastodon.
- Cursor + Mastodon
Set up Cursor to post to Mastodon.
- X MCP server
280 characters per post, counted the way X counts: links are 23 and most emoji are 2.
- LinkedIn MCP server
Up to 3,000 characters. Only the first few lines show before "see more".
- Bluesky MCP server
300 characters per post, counted as you'd count them by eye.
- Mastodon scheduler
Posts and threads on any instance, up to 500 characters.
Ready to get started?
Connect your AI tool in a minute. It schedules your Mastodon posts, and you see every one in your calendar.
Cancel anytime · or self-host for free
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