Post to Mastodon from Grok Build
Grok Build can post to Mastodon on Mastodon through ClipSpeed. Add the ClipSpeed server with one config block, sign in, and then ask Grok Build to post to Mastodon, pick the time, and apply Mastodon's settings, without leaving xAI's coding agent and CLI. Mastodon is on the roadmap on ClipSpeed's rail; this page describes how it works and says so.
Keep a human in the loop: Grok Build shows the plan and asks before anything is public. Posting today: YouTube, TikTok, Instagram, X (Twitter) and LinkedIn.
Also try
How to post Mastodon from Grok Build
Add ClipSpeed as an HTTP MCP server in Grok Build's configuration, complete the sign-in, and the tools appear. Connect Mastodon in ClipSpeed, then describe the post. Setup takes about a minute.
# One-time setup: Grok Build MCP config
{
"mcpServers": {
"clipspeed": { "url": "https://api.clipspeed.ai/mcp" }
}
}
# Then ask Grok Build:
> Post the announcement to Mastodon at 9am
Grok Build: Preview — nothing booked yet. Mastodon — text under 500. Book it?ClipSpeed has not yet run an end-to-end check inside Grok Build. The server is standard MCP over HTTP; the configuration shape above is the common one and Grok Build's documentation is the reference for the file location.
- Add the clipspeed server with the URL to Grok Build's MCP configuration (see its docs for the file location).
- Start Grok Build; complete the ClipSpeed sign-in when prompted, or use an API key header.
- Ask it to list your channels.
- Connect Mastodon in the ClipSpeed app, or ask Grok Build for a connect link: it is private, valid for ten minutes, and Mastodon signs you in itself.
What can Grok Build do on Mastodon?
On Mastodon, Grok Build can post 500-character text, images and video to a Mastodon account on any server. Every booking runs through the same rules as the ClipSpeed app.
Text, Image and Video posts
Mastodon takes text, image and video through ClipSpeed. Video: MP4 or WebM. Image: JPG, PNG or GIF; up to four per post on Mastodon.
500 characters, checked at booking
Mastodon's own arithmetic, with every link counted as 23. Too long is refused with the real count, never trimmed at send time.
Exact time or refused
Name the minute and Grok Build books it, or you are told why not and offered the next open slot. A booked Mastodon post is never moved behind your back.
Preview before anything posts
preview: true runs the whole booking and writes nothing. Grok Build shows the plan, with each slot and the day's remaining cap, and books only on your yes.
Clips cut in the same session
Submit a video or stream link, get captioned 9:16 clips with a viral score, and post the best as native video on Mastodon. No download, no re-upload.
Pacing and numbers
Planned: Text posts on Mastodon are at least 30 minutes apart, up to 10 a day. Video on Mastodon is at least 4 hours apart, up to 4 a day under your plan. After a post goes out, Grok Build can read back views and engagement where Mastodon provides them.
How does Grok Build post to Mastodon through ClipSpeed?
You describe what you want in plain language and Grok Build makes the ClipSpeed calls. A typical conversation has three beats.
Find your Mastodon channel
Ask Grok Build whether Mastodon is connected. It calls list_channels and reads platform_settings, so it also knows what Mastodon accepts and the limits before you write a word.
Compose within the rules
Describe the post. Grok Build drafts within Mastodon's limits, counting links as 23; mention a clip or a file and it attaches it.
Schedule or publish
Name a time, or say now. The slot is booked exactly or refused with the next open one, and the reply carries the id you can cancel or edit by.
Mastodon settings reference
These are the schedule_post fields that apply to Mastodon. Mention any of them in plain language and Grok Build sets them; the server checks them at booking. Fields marked planned land with the Mastodon release.
| Field | Type | Required | What it does on Mastodon |
|---|---|---|---|
platforms | string[] | Yes | Include "mastodon". Up to ten platforms per call; each books its own slot. |
text | string | Yes for a text post | Up to 500 characters on a default server; links count as 23. |
visibility | public | unlisted | followers | Planned | Mastodon's post visibility. |
media_kind | text | image | video | No | Detected from the file when omitted. |
clip_id or media_url | string | No | A clip or a public link. |
scheduled_at | ISO 8601 | No | Exact or refused with the next open slot. |
preview | boolean | No | Plan only. |
Common Mastodon configurations
Ask Grok Build for any of these and it applies the matching settings.
Public post
Unlisted test
Clip as video
Day of posts, previewed
Example prompts for Mastodon in Grok Build
Type these into xAI's coding agent and CLI. Grok Build calls ClipSpeed and confirms before publishing.
Post Mastodon with a scheduled time
Post the announcement to Mastodon at 9am. Keep the text under 500 characters with links counted as 23. Preview first.
Cut the clips, then post the best
Clip this link, keep the top three by viral score, and schedule them to Mastodon at 11am, 3pm and 7pm tomorrow. Show me the plan before booking.
Check and adjust the Mastodon calendar
What is scheduled on Mastodon this week? Cancel tomorrow's post and tell me the next open Mastodon slot on Friday.
Mastodon limits and gotchas to know
Mastodon enforces a few rules that Grok Build and ClipSpeed respect automatically, but knowing them helps you phrase requests.
- 500 characters is the default limit, with every link counted as 23. Some servers allow more; ClipSpeed will use your server's limit at booking.
- Your account lives on one server; you connect that server, not mastodon.social in general.
- Mastodon is on ClipSpeed's roadmap, not the next rail. Bookings are refused plainly until it posts.
- Content warnings and alt text are planned fields.
- Planned pacing: ten text posts a day 30 minutes apart, video four hours apart.
| Rule | Mastodon |
|---|---|
| Accepts | Text, Image, Video |
| Text limit | 500 characters; every link counts as 23 (500 is the default; your server may allow more) |
| Title | No title field |
| Links in the caption | Kept; every link counts as 23 characters |
| Pacing | Planned: Text posts on Mastodon are at least 30 minutes apart, up to 10 a day. Video on Mastodon is at least 4 hours apart, up to 4 a day under your plan. |
| Formats | Image: JPG, PNG or GIF; up to four per post on Mastodon. Video: MP4 or WebM. Aspect: any |
| Status | On the roadmap; described here, not yet bookable |
What Postiz-style schedulers cannot do
Cut the clips first
Grok Build does not need finished video to start. Hand it a YouTube link, a podcast, a stream VOD or a local export. ClipSpeed finds the moments, cuts them to 9:16 with word-by-word captions, scores each one 0 to 100 for shareability, and returns them in the same conversation. Grok Build picks by score, writes the caption from the transcript, and books the clips on Mastodon. Three tool calls, one approval, no download and no re-upload.
- Clips arrive with a title written from the hook, a transcript and a viral score, so the agent can choose and caption without watching the footage.
- Live streams can be clipped while they are still on air; the agent books the highlights for the next morning before the stream ends.
- Every clip is already hosted, so
schedule_posttakes its id directly. Nothing moves through your laptop.
submit_to_clipspeedPaste the link. ClipSpeed starts the job and returns a project id.check_clipsPoll with the project id. Back come the finished 9:16 clips with titles, transcripts, viral scores and preview links.schedule_postPass the clip id, the platforms, a caption and a time. Grok Build shows the plan with preview: true, you say yes, it books.generate_image or generate_videoDescribe the shot. ClipSpeed runs it on the model that fits (Seedance, Kling, Veo, Nano Banana Pro, GPT Image and others) and quotes the credits first.wait_for_generationReturns the hosted result link and a preview the agent can show you.schedule_post with media_urlThe result link goes straight into the booking on Mastodon. The caption, the time and the file are approved together.The other half nobody else has
Generate the image or video, then post it
A product shot for Instagram, a 16:9 announcement graphic for X, a six-second opener before a clip: Grok Build can make an image or a short video with ClipSpeed's image and video models and book the result in the same reply. There is no separate design tool, no export, no upload page. The generated file is hosted, so media_url is the only thing the booking needs.
- The price in credits is quoted before anything renders, within the per-generation and daily caps you set in Settings.
- Results are previewed in the conversation, so you approve the picture and the post at once.
- Images post as JPG, PNG or WebP up to 25 MB; video posts as MP4, MOV or WebM up to 1 GB.
What is Grok Build?
Grok Build is xAI's coding agent and command-line tool. It runs tasks in your project and can call MCP servers. With ClipSpeed added, it can clip a video, generate media and schedule posts.
How ClipSpeed works with Grok Build
- Connects over HTTP
- Reads platform rules
- Exact-or-refused booking
preview: true- Same tools everywhere
Grok Build vs Grok Bot vs Grok: Grok Build (terminal), Grok Bot (cloud, always on), Grok (x and grok.com). This page is about Grok Build; the Grok Build guide compares them.
{
"mcpServers": {
"clipspeed": {
"url": "https://api.clipspeed.ai/mcp"
// or: "headers": { "Authorization": "Bearer csai_live_..." }
}
}
}# What the agent reads at connect time (tool descriptions, abridged)
list_channels Connected platforms, what each accepts, limits, your time zone
connect_channel A private 10-minute link to connect one platform
platform_settings Limits, title rules, link handling, pacing per platform
schedule_post clip_id | text | media_url → platforms[], scheduled_at, preview
list_scheduled_posts Scheduled, sending, posted, failed — with post links
update_scheduled_post Edit copy while still scheduled (the time never moves)
cancel_scheduled_post Cancel; undoable 72 h in the app
post_analytics Views, likes, comments, shares where the platform gives them
submit_to_clipspeed Start clipping a video or stream link → projectId
check_clips Finished 9:16 clips with titles, transcripts, viral scores
generate_image / generate_video / wait_for_generation
# Mastodon: text/image/video · text 500 (links = 23)Post to Mastodon and other platforms from Grok Build
One request can book the same content to Mastodon and other channels, each keeping its own settings and its own slot. Every platform below has its own Grok Build guide.
Also works with
Mastodon and Grok Build: frequently asked questions
How do I post to Mastodon from Grok Build?
Add the clipspeed server with the URL to Grok Build's MCP configuration (see its docs for the file location). Start Grok Build; complete the ClipSpeed sign-in when prompted, or use an API key header. Connect Mastodon in ClipSpeed (or ask Grok Build for a connect link; it is private and valid for ten minutes), then describe the post in plain language. Grok Build reads the Mastodon rules, drafts within them, shows the plan and books on your yes. Mastodon is on the roadmap; until the badge changes, the booking is refused with a plain message.
What can Grok Build post to Mastodon through ClipSpeed?
Post 500-character text, images and video to a Mastodon account on any server. Mastodon takes text, image and video posts. Text is limited to 500 characters, with every link counted as 23.
Which Mastodon settings can Grok Build control?
The fields in the settings reference above: text, visibility, media_kind, clip_id or media_url, scheduled_at, preview. Mention any of them in plain language ("unlisted", "tomorrow at 9", "preview first") and Grok Build sets the matching field before it books.
Do I need a Mastodon API key or developer account?
No. You connect Mastodon to ClipSpeed once through Mastodon's own sign-in, and Grok Build talks to ClipSpeed over OAuth. No Mastodon developer key, bearer token or password is pasted anywhere.
How many Mastodon posts a day can Grok Build schedule?
Planned: Text posts on Mastodon are at least 30 minutes apart, up to 10 a day. Video on Mastodon is at least 4 hours apart, up to 4 a day under your plan. When a time is taken, the booking is refused with the next open slot rather than moved. Ask for preview to see a day's plan and the remaining cap before anything is booked.
Can posts go out to Mastodon while I am away?
Yes. Once booked, ClipSpeed publishes at the scheduled minute whether or not Grok Build is open. For unattended runs that decide what to post, use a headless agent such as Claude Code or Codex with the same account.
Is posting to Mastodon from Grok Build different from Grok Bot?
The booking is identical: the same rules, the same calendar, the same refusals. What differs is where you work. Grok Build: terminal. Grok Bot: cloud, always on, routines on a cloud computer.