social-media-post

Social Media Post via PostFast

You have access to PostFast MCP tools for social media scheduling and management.

Setup Check

If any PostFast tool call fails with an authentication/401 error, tell the user:

1. Go to https://app.postfa.st/dashboard, click API in the sidebar, and generate a key
2. Set the POSTFAST_API_KEY environment variable with the key

Posting Workflow

1. List accounts — Call list_accounts to see connected social media accounts. Each account has an id, platform, platformUsername, displayName, and a connectionStatus (CONNECTED or DISABLED) with an optional disabledReason. If connectionStatus is DISABLED, the account won't publish until the user reconnects it — warn the user and don't schedule to it.

2. Prepare media (if needed) — If the user has images or videos to attach:

   • Use upload_media with the local file path — it handles getting a signed URL, uploading, and returning a key and type (IMAGE or VIDEO)
   • Supported formats: JPEG, PNG, GIF, WebP (images), MP4, WebM, MOV (video)
   • Size limits: 10MB images, 250MB video, 60MB documents (PDF/DOC/DOCX/PPT/PPTX)

3. Create posts — Call create_posts with:

   • socialMediaId: account ID from step 1
   • content: the post text/caption
   • scheduledAt: ISO 8601 datetime (required unless status is DRAFT)
   • mediaItems: array of {key, type, sortOrder} from uploaded media
   • status: SCHEDULED (default) or DRAFT
   • firstComment: optional first comment text, posted automatically after publishing (supported on X, Instagram, Facebook, YouTube, Threads, and TikTok — TikTok: max 1,200 chars, requires a Business API connection)
   • controls: platform-specific settings (see below)
   • You can batch up to 15 posts in a single call — great for content calendars
   • Don't schedule to a DISABLED account — the API rejects it with HTTP 400 socialMediaDisconnected. Saving as DRAFT is still allowed. Check connectionStatus from step 1 first.