Schedule social posts from Claude

# posterly for Claude

posterly is the publish layer. Claude is the chat layer. Add a custom connector on claude.ai, or local stdio in Claude Desktop and Claude Code.

posterly publishes to 18 platforms: Instagram, Facebook, TikTok, X, LinkedIn, YouTube, Pinterest, Threads, Google Business, Telegram, Bluesky, Discord, Slack, Mastodon, Dev.to, Hashnode, WordPress, Lemmy.

## Connect

claude.ai: Customize, Connectors, Add custom connector, paste https://www.poster.ly/api/mcp. Free plans can add one custom connector. Writes run after user approval.

Claude Code: `claude mcp add --transport http posterly https://www.poster.ly/api/mcp` or stdio `claude mcp add --scope user -e POSTERLY_API_KEY=pst_live_your_key_here posterly -- npx -y posterly-mcp-server@latest`.

Claude Desktop: claude_desktop_config.json with the npx stdio block.

This is a custom connector you add yourself. Do not look for a directory listing.

Stdio file_path uploads work in Claude Desktop and Claude Code, not on claude.ai. Chat attachments never reach MCP.

## Are we connected yet?

1. Call `whoami` (no params). Confirm the user, scopes, and workspaces.
2. Call `list_accounts` (`workspace_id` optional). If none are connected, stop and send the user to connect social accounts in posterly. Do not invent account IDs.
3. Prefer `validate_post` before `create_post`. Show the preview. Wait for a clear yes.
4. Only then call `create_post` with `confirm: true`. Never publish or schedule live without that approval.
5. Prefer `scheduled_at` (ISO 8601 UTC) or `find_available_slot` (`account_ids`, `timezone`, `count`). Do not publish immediately unless the user asks.

## Rules

- posterly is the publish layer. This client is the chat or agent layer.
- Never collect card details, posterly passwords, or social-network passwords. Send the user to https://www.poster.ly/agents/signup or https://www.poster.ly/dashboard/api.
- Point to https://www.poster.ly/mcp for the rest of the 86 hosted HTTP MCP tools (89 on the local stdio package).
- After a post is created, send the View in posterly link. Avoid raw JSON dumps unless the user asks to debug.

## Media (honest)

Chat attachments never reach MCP. The paperclip in this chat does not give posterly the file.

The ~4MB limit is the **Vercel request body** on posterly API routes (`/api/mcp`, `POST /api/v1/media/upload`). It is not an MCP protocol cap and not the plan storage cap. Base64 inflates files, so hosted `upload_media` is small images only (relay cap 5MB decoded).

- Public HTTPS URL: `upload_media_from_url` (`url`, optional `filename`, `content_type`) or pass `media_url` / `media_urls` on `validate_post` / `create_post`. Server fetch: about 5MB relay, 60MB hard cap. Large R2/S3 URLs fail with `remote_media_too_large`.
- Hosted `upload_media`: required `filename` + `base64_data`. Optional `content_type`. Hits the 4MB Vercel body. JPEG, PNG, GIF, WebP, MP4, MOV, WebM. HEIC is unsupported.
- Laptop file in ChatGPT web or Claude.ai: `create_media_drop` (optional `filename`, optional `max_files`, default 10). Send the user `drop_url` (`https://www.poster.ly/drop/<token>`). They open it with no dashboard login and drop the file. Then `list_media` (`drop_session_id`) and pass `public_url` to `validate_post` / `create_post`. This is not the chat paperclip.
- Larger files, when this client can HTTP PUT: `create_signed_upload` (`filename`, `content_type`, `size`), PUT the raw bytes to the returned `upload_url` (object storage, not a posterly API route) with the returned headers, then pass `public_url` to `create_post`. That PUT does not hit the 4MB body. Plan video caps: Starter 500MB, Pro 750MB, Power 1GB, Agency 4GB.
- Stdio `upload_media` also accepts `file_path` when the user gives a real local filesystem path. The local server reads the disk and uses signed upload for large files, so this does not hit the Vercel 4MB body. Never guess paths. Chat attachments are not a file_path.

## Starter tools

- `whoami` (none): Call first. Returns the authenticated user, API key scopes, and workspaces.
- `list_accounts` workspace_id?: Connected social accounts. Stop if this is empty and send the user to connect accounts in posterly.
- `validate_post` account_id or username+platform, caption, scheduled_at?, media_url?, media_urls?, post_type?, workspace_id?: Dry run. Does not create a post. Use this before showing a preview.
- `create_post` same as validate_post, plus confirm: true (required): Destructive write. Refuse unless the user clearly approved caption, account, media, and schedule.
- `upload_media` filename, base64_data (hosted). content_type optional. Stdio also accepts file_path.: Hosted path is base64 with a decoded file of 5MB or less. Chat paperclip files never arrive here.
- `upload_media_from_url` url (required), filename?, content_type?: Fetch a public HTTPS URL into posterly storage. Localhost and private IPs are blocked.
- `create_signed_upload` filename, content_type, size: Bypasses the Vercel ~4MB API body. Returns upload_url (object storage) and public_url. PUT raw bytes to upload_url, then pass public_url to create_post. Use this when the client can PUT (Cursor, Claude Code, Codex).
- `create_media_drop` filename?, max_files?: Creates a no-login page at https://www.poster.ly/drop/<token>. Send drop_url to the user. ChatGPT web and Claude.ai laptop files use this, then list_media. Not the chat paperclip.
- `list_media` limit?, drop_session_id?: Newest media assets. After create_media_drop, pass drop_session_id and use public_url on validate_post / create_post.
- `find_available_slot` account_ids?, timezone?, workspace_id?, count?: Always pass timezone explicitly (IANA, e.g. Europe/London). Respects a 1-hour gap.
- `generate_captions` platforms (required), brief?, tone?, count?, mode?, source_caption?: Returns caption options only. It does not schedule or publish.
- `list_posts` status?, platform?, account_id?, workspace_id?, limit?: Upcoming or recent posts. status is scheduled, published, failed, or draft.

## Example prompts

- Using posterly, run whoami and list_accounts. Which LinkedIn and Instagram accounts can I post to?
- Draft a LinkedIn, X, and Instagram launch post. Find the next free slot in Europe/London, run validate_post for each, and wait for my approval.
- Write three caption options for this product update with generate_captions. Do not schedule anything yet.
- List scheduled posts for this week and suggest one gap I could fill on LinkedIn.
- After I approve, create_post the LinkedIn draft with confirm true and send me the View in posterly link.
- I have a public image URL. upload_media_from_url, then validate_post an Instagram image post for tomorrow 9:00 Europe/London. Wait for my yes.
- I have a video on my laptop. Call create_media_drop, send me the /drop/ link, wait, then list_media and validate_post. Do not use the paperclip.
- Do not publish live. Prefer scheduled_at or find_available_slot unless I explicitly ask to post now.

## Links

- Human landing: https://www.poster.ly/claude
- MCP hub: https://www.poster.ly/mcp
- Claude guide: https://www.poster.ly/guides/claude-guide
- AI agents: https://www.poster.ly/agents
- Agent signup: https://www.poster.ly/agents/signup