Post to Mastodon from Claude

Claude drafts it. You approve it. PostDelegate posts it.Mastodon: Posts and threads on mastodon.social, with images or a video.

How to post to Mastodon from Claude

Add PostDelegate to Claude. In Claude open Settings, then Connectors, then Add custom connector. Name it PostDelegate and paste the server URL below. Choose Add, then Connect, sign in to PostDelegate and click Authorize.
Server URL
```
https://app.postdelegate.com/mcp-oauth-dynamic
```
Custom connectors depend on your Claude plan and, on team plans, on what your organisation allows.
Connect Mastodon in PostDelegate. On the calendar page choose Add Channel, then Mastodon. Sign in to your mastodon.social account and approve the permissions PostDelegate asks for: reading your profile, publishing posts and uploading media.
Ask Claude for a draft. Describe the post in plain words. Claude checks your Mastodon channel's rules, creates the post and sends back a preview link.

Teach Claude the posting rules

Add the PostDelegate skill to Claude so it knows the posting rules before it writes: download the skill zip and upload it under Customize, then Skills, with code execution turned on. Agent files has the steps.

What to ask Claude

Mention any Mastodon setting in plain words and Claude fills it in. Start with something harmless, like asking which channels you have.

Draft a Mastodon post about our open-source release, under 500 characters, with two relevant hashtags.
Which Mastodon posts do I have scheduled next week? Move nothing, just list them.

What Claude can do on your Mastodon channel

Check the rules first. Before writing, it reads your Mastodon channel's length limit (500 characters) and required settings.
Draft, schedule or post. It creates a draft, a scheduled post or an immediate post, and runs the same checks as the app.
Use your media. It attaches files from your media library or adds one from a public link.
Review and fix. It lists what is scheduled, changes the Mastodon settings of a post that has not gone out, and deletes posts you no longer want.

A Mastodon post is up to 500 characters with up to four images or one video. PostDelegate keeps the text and media together with the planned post, publishes it as a public post at the time you pick, and turns extra entries into a thread of replies.

Before you start

PostDelegate connects accounts on mastodon.social. Accounts on other Mastodon servers cannot be connected yet.
Posts are published as public posts, limited to 500 characters with up to four images or one video.

The Mastodon channel guide has every field, and MCP tools lists exactly what an assistant can and cannot do.

Questions

Will Claude publish to Mastodon without asking me?

Not unless you ask it to. Ask for a draft and the post waits on your calendar until you schedule it, and your workspace's approvals apply as usual. Tools that change data are marked as such, so Claude can ask you before it schedules or deletes anything.

Do I need an API key to connect Claude?

No. Claude signs in with your PostDelegate account through your browser. An API key is only for clients that cannot sign in, as described in MCP clients.

Does it cost extra to use Claude with PostDelegate?

No. The MCP server is on every plan, and Claude runs on your own Claude account, so PostDelegate never charges for AI. Every plan starts with a 7-day free trial with no card.

Can Claude attach images or video to a Mastodon post?

It can use files already in your media library, or add one from a public link. It cannot fetch files from your computer, so upload those in the app first, or through the upload widget where Claude shows it. See MCP tools.

Can I connect an account on another Mastodon server?

Not yet. PostDelegate connects accounts on mastodon.social. Accounts on other Mastodon servers cannot be connected today.

Can I schedule a Mastodon thread?

Yes. Add more entries to the post with Add post in a thread, and they are published as replies to the first post.

Mastodon from other assistants

Other networks from Claude

Prefer to plan Mastodon posts yourself? See the Mastodon scheduler.