| name | publish-substack-note |
| description | Publish a short-form Substack Note (300-600 words) with an optional hero image, using the Claude-in-Chrome extension (Playwright gets 403 on Substack). Use when you have approved note content ready to post. |
| version | 1.0.0 |
| author | Bubble Invest |
| license | MIT |
| disable-model-invocation | true |
Publish a Substack Note
You receive: note text (300-600 words) + optional hero image. You publish it as a Substack Note.
Method — Claude-in-Chrome extension
Playwright gets a 403 on Substack. Use the Chrome-extension MCP tools (a logged-in browser session) instead.
Step-by-step
osascript -e 'set the clipboard to (read (POSIX file "/path/to/hero.jpg") as JPEG picture)'
Then use the Chrome-extension MCP tools:
# 2. Get tab context
tabs_context_mcp(createIfEmpty=true) -> tabId
# 3. Navigate
navigate(url="https://substack.com/home", tabId=tabId)
# 4. Click the composer ("What's on your mind?" / your locale's equivalent)
click(<composer prompt>)
# 5. Click inside the composer area
click(coordinate=[530, 400])
# 6. IMAGE FIRST (if any) — paste from clipboard
key("cmd+v") -> wait 5 seconds
# 7. TEXT SECOND — type (do NOT paste/fill)
type(text="note content here")
# 8. Click the orange "post" button (bottom-right of the composer)
# Take a screenshot first to locate its exact position
click(coordinate=[772, 672])
Critical rules
- Image FIRST, text SECOND. Pasting text first can clobber the pending image.
- Use the
type action, never paste text (pasting can disturb the image).
- The "post" button position varies — take a screenshot to locate it before clicking.
- Playwright does NOT work for Substack (403) — always use the Chrome extension.
Note format guidelines
- 300-600 words max
- One idea, one angle, one conclusion
- Match your own publication's voice and language
Pre-publish QA checklist
