# Substack API and MCP server

> Substack has only a limited API (checked 11 Oct 2026). Its Developer API looks up public creator profiles after approval, and there is no public API to write posts or Notes, manage subscribers or send email. RSS reads public posts only.

Newsletter and publishing platform for writers: posts sent by email, Notes, comments, and free and paid subscriptions.

## What is the Substack API?

Cotlet's Substack API exposes 14 endpoints for your own Substack account: list posts, get post, get post stats, get publication stats, list subscribers, export subscribers, list comments, create draft, update draft, schedule post, publish post, publish Note, reply to comment and add subscriber. The list_posts endpoint returns posts of your publication, newest first, with status and audience. Each endpoint takes simple JSON inputs like post_id, limit or cursor and works both as an MCP tool for agents and as a REST call for scripts.

- **Category:** [Creators & communities](https://cotlet.dev/integrations/category/creators-communities)
- **Endpoints:** 14 (7 read, 7 write)
- **Updated:** 2026-10-11

Substack has only a limited API (checked 11 Oct 2026). Cotlet is a hosted MCP server and REST API for Substack with 14 endpoints (7 read, 7 write): your AI agent signs in as you and does the work.

## Does Substack have an official API?

Substack has only a limited API (checked 11 Oct 2026). Its Developer API looks up public creator profiles after approval, and there is no public API to write posts or Notes, manage subscribers or send email. RSS reads public posts only.

| Task | Substack official | Cotlet |
|---|---|---|
| Create and edit drafts | No | Yes |
| Publish or schedule posts | No | Yes |
| Publish or schedule Notes | No | Yes |
| Add or export subscribers | No: Dashboard only: CSV import and export | Yes |
| Post and publication stats | No: Dashboard only, exportable as CSV | Yes |
| Reply to comments | No | Yes |
| Read your published posts | Partly: Public RSS feed, no drafts or paywalled text | Yes |

Sources: [Substack Developer API Terms of Use](https://substack.com/api-tos), [Substack features (scheduling, import, export, Notes, stats)](https://substack.com/features), [On Substack: you can now schedule Notes](https://on.substack.com/p/new-on-substack-post-templates-notes), [Substack help: Do you support Markdown? (post editor)](https://support.substack.com/hc/en-us/articles/360037463132-Do-you-support-Markdown), [Substack help: A guide to Substack metrics](https://support.substack.com/hc/en-us/articles/5320347155860-A-guide-to-Substack-metrics)

## For AI agents

```text
Substack has only a limited API (checked 11 Oct 2026). Its Developer API looks up public creator profiles after approval, and there is no public API to write posts or Notes, manage subscribers or send email. RSS reads public posts only.
Cotlet provides a hosted MCP server and REST API for Substack: 14 tools (7 read, 7 write).
Access       Request access at https://cotlet.dev/app/signup?app=substack; we email the API key.

MCP server   https://cotlet.dev/mcp/v1
REST base    https://cotlet.dev/api/v1/substack
Auth         Authorization: Bearer <COTLET_API_KEY>. Listing endpoints and schemas needs no key; calling an endpoint needs one.
Tools        list_posts, get_post, get_post_stats, get_publication_stats, list_subscribers, export_subscribers, list_comments, create_draft, update_draft, schedule_post, publish_post, publish_note, reply_to_comment, add_subscriber
Confirm      schedule_post, publish_post, publish_note, reply_to_comment, add_subscriber (by default the user approves each call; the user can switch this off per tool, e.g. for scheduled automations)
Markdown     https://cotlet.dev/integrations/substack-api-mcp-server.md

How access works:
1. The user requests access at https://cotlet.dev/app/signup?app=substack (Substack is pre-selected). Each request is reviewed and the API key is sent by email.
2. The user signs in to Substack once in a browser. An agent cannot do this step.
3. The API key goes into the MCP client or the REST call as a bearer token.

Fits: people who want a hosted Substack server that someone else maintains, including non-developers. Developers who prefer to run and fix code on their own computer can use an open-source Substack MCP server instead.

Policy: Cotlet never stores passwords, never solves CAPTCHAs, never bypasses MFA.
Company: legal details in the Terms of service at https://cotlet.dev/terms. Contact contact@cotlet.dev.
Session: the user signs in to Substack in a browser; Cotlet keeps only the session, AES-256 encrypted, revocable in the dashboard at any time.
Terms: the user stays responsible for following Substack's terms; Cotlet is not affiliated with Substack.
```

## What can an AI agent do in Substack?

Cotlet is best for newsletter writers who schedule posts, Notes and replies every week without running or fixing a server.

- **[Schedule newsletter posts from a Markdown draft](https://cotlet.dev/integrations/substack-api-mcp-server/schedule-newsletter-posts)** (runs: weekly): "Turn essay.md into a Substack draft for everyone, schedule it for Tuesday 8:00 New York time, and schedule a Note with a link card to it for 12:00 the same day." → `list_posts`, `create_draft`, `schedule_post`, `publish_note`
- **Post a Note when a new post goes out**: "Post a Note teasing today's essay, with a link card to it." → `list_posts`, `publish_note`
- **[Weekly subscriber growth and revenue report](https://cotlet.dev/integrations/substack-api-mcp-server/weekly-subscriber-report)** (runs: weekly): "Every Monday at 8:00, send me last week's Substack numbers: new free and paid subscribers, churned paid subscribers, revenue, and how each post from the week did on opens and new subscribers." → `get_publication_stats`, `list_posts`, `get_post_stats`
- **[Reply to comments nobody answered](https://cotlet.dev/integrations/substack-api-mcp-server/reply-to-unanswered-comments)** (runs: daily): "Every evening, find comments on my last three Substack posts that I have not answered, draft a short reply to each in my voice, and show me the drafts before posting." → `list_posts`, `list_comments`, `reply_to_comment`
- **Add event signups as subscribers**: "Add everyone from workshop.csv as free subscribers." → `add_subscriber`

## Can Substack automations run on a schedule in n8n, Make or Zapier?

Yes. Cotlet does not replace your automation platform: it gives it a Substack connection it does not have, with the same API key as your agent. Write actions ask for your OK by default; switch that off in your dashboard for the tools you choose, for example to schedule newsletter posts from a markdown draft, and the schedule runs on its own. Cotlet runs in the cloud, so it keeps going while your computer is off.

| Where | How to connect | How to schedule |
|---|---|---|
| Your AI agent | Add https://cotlet.dev/mcp/v1 with your API key. | A scheduled agent run, for example a Claude Code routine. |
| n8n | MCP Client node with https://cotlet.dev/mcp/v1, or an HTTP Request node to https://cotlet.dev/api/v1/substack/{tool}. | Schedule Trigger node. |
| Make | HTTP module: POST https://cotlet.dev/api/v1/substack/{tool} with an Authorization: Bearer header and a JSON body. | Scenario schedule. |
| Zapier | Webhooks by Zapier: POST https://cotlet.dev/api/v1/substack/{tool} with the same header and body. | Schedule by Zapier trigger. |
| Your own script | POST https://cotlet.dev/api/v1/substack/{tool} with your API key. | cron or GitHub Actions. |

## Tools

**For AI agents:** Every endpoint and its schema is public. The 14 endpoints on this page, with parameters and example responses, can be listed without an account. Calling one returns 403 until the account has an API key with access to Substack.

### list_posts

Posts of your publication, newest first, with status and audience. Access: read. REST: `POST /api/v1/substack/list_posts`.

| Parameter | Type | Required | Description |
|---|---|---|---|
| `status` | enum | no | published, draft or scheduled. Default: published. |
| `limit` | integer | no | 1 to 50. Default: 20. |
| `cursor` | string | no | Next page cursor from the previous call. |

Lists posts of your publication, newest first. Filter by status to see drafts or scheduled posts. Scheduled posts include their publish time. Pages hold up to 50 posts; pass next_cursor back as cursor for the next page.

Example response:

```json
{
  "posts": [
    {
      "post_id": "148213977",
      "title": "The quiet launch",
      "status": "published",
      "audience": "everyone",
      "published_at": "2026-10-06T12:00:00Z",
      "url": "https://yourname.substack.com/p/the-quiet-launch"
    },
    {
      "post_id": "148420031",
      "title": "Notes on pricing",
      "status": "draft",
      "audience": "only_paid",
      "published_at": null,
      "url": null
    }
  ],
  "next_cursor": "eyJvZmZzZXQiOjIwfQ"
}
```

### get_post

Full post: title, subtitle, body as Markdown, audience, URL and dates. Access: read. REST: `POST /api/v1/substack/get_post`.

| Parameter | Type | Required | Description |
|---|---|---|---|
| `post_id` | string | yes | Post ID from list_posts. |

Returns one post with its full body as Markdown, including the paywalled part of your own posts. Use it to edit a published post or to quote it in a Note. Images come back as URLs.

Example response:

```json
{
  "post_id": "148213977",
  "title": "The quiet launch",
  "subtitle": "What waiting taught me",
  "body_markdown": "Last month I shipped without telling anyone...",
  "audience": "everyone",
  "status": "published",
  "published_at": "2026-10-06T12:00:00Z",
  "url": "https://yourname.substack.com/p/the-quiet-launch"
}
```

### get_post_stats

Recipients, opens, open rate, views, likes, restacks and subscribers gained. Access: read. REST: `POST /api/v1/substack/get_post_stats`.

| Parameter | Type | Required | Description |
|---|---|---|---|
| `post_id` | string | yes | Post ID from list_posts. |

Returns the engagement numbers of one published post, the same as its stats page in the dashboard. Email numbers cover the send; views include the web. Numbers keep growing for days after a send, so check again later.

Example response:

```json
{
  "post_id": "148213977",
  "recipients": 4120,
  "opens": 2011,
  "open_rate": 0.488,
  "views": 3560,
  "likes": 142,
  "restacks": 18,
  "subscribers_gained": 37
}
```

### get_publication_stats

Total, paid, new and churned subscribers and revenue for a period. Access: read. REST: `POST /api/v1/substack/get_publication_stats`.

| Parameter | Type | Required | Description |
|---|---|---|---|
| `period` | enum | no | 7d, 30d or 90d. Default: 30d. |

Returns subscriber and revenue numbers for a period, the same figures as the publisher dashboard: total, paid and new subscribers, churned subscribers and revenue. Periods are 7, 30 or 90 days.

Example response:

```json
{
  "period": "7d",
  "subscribers_total": 4380,
  "subscribers_paid": 412,
  "subscribers_new": 96,
  "subscribers_churned": 11,
  "revenue_usd": 3150
}
```

### list_subscribers

Subscribers with plan, start date and activity rating. Access: read. REST: `POST /api/v1/substack/list_subscribers`.

| Parameter | Type | Required | Description |
|---|---|---|---|
| `plan` | enum | no | all, free, paid, comp or founding. Default: all. |
| `since` | date | no | Only subscribers who joined on or after this date. |
| `limit` | integer | no | 1 to 500. Default: 100. |
| `cursor` | string | no | Next page cursor from the previous call. |

Lists subscribers, newest first. Filter by plan or by the date they joined. Activity rating is the 0 to 5 score Substack shows in the subscriber dashboard. Pages hold up to 500 subscribers; pass next_cursor back as cursor.

Example response:

```json
{
  "subscribers": [
    {
      "email": "maya@example.com",
      "plan": "free",
      "joined_at": "2026-10-04T09:12:00Z",
      "activity_rating": 4
    },
    {
      "email": "jon@example.com",
      "plan": "paid",
      "joined_at": "2026-10-02T17:40:00Z",
      "activity_rating": 5
    }
  ],
  "next_cursor": null
}
```

### export_subscribers

The full subscriber list as a CSV download link, valid for 1 hour. Access: read. REST: `POST /api/v1/substack/export_subscribers`.

No parameters.

Builds the same CSV as Export in the subscriber dashboard and returns a link to it. Use it for the full list; list_subscribers is better for filtered pages. The link stops working after 1 hour.

Example response:

```json
{
  "download_url": "https://files.cotlet.example/exports/subscribers-2026-10-11.csv",
  "rows": 4380,
  "expires_at": "2026-10-11T13:00:00Z"
}
```

### list_comments

Comments on a post, with author, text and whether you replied. Access: read. REST: `POST /api/v1/substack/list_comments`.

| Parameter | Type | Required | Description |
|---|---|---|---|
| `post_id` | string | yes | Post ID from list_posts. |
| `unanswered_only` | boolean | no | Skip threads you already replied to. |

Returns the comments of one post, oldest first, with replies nested under their parent. Set unanswered_only to skip threads you already replied to. Pass comment_id from an item to reply_to_comment.

Example response:

```json
{
  "comments": [
    {
      "comment_id": "c_90417",
      "author": "Maya Chen",
      "body": "Does the next part cover pricing?",
      "created_at": "2026-10-07T08:20:00Z",
      "replied": false,
      "replies": []
    }
  ]
}
```

### create_draft

New draft from Markdown. Nothing is sent until you publish or schedule it. Access: write. REST: `POST /api/v1/substack/create_draft`.

| Parameter | Type | Required | Description |
|---|---|---|---|
| `title` | string | yes | Post title. |
| `body_markdown` | string | yes | Post body. Images by URL. |
| `subtitle` | string | no | Shown under the title and in the email preview. |
| `audience` | enum | no | everyone, only_paid or founding. Default: everyone. |

Creates a draft in your publication and returns its post_id. The draft is visible only to your team. Sending is a separate step: schedule_post or publish_post. Creating a draft reaches no one and update_draft or the Substack editor changes it, so it runs without asking.

Example response:

```json
{
  "post_id": "148420031",
  "status": "draft",
  "audience": "everyone",
  "edit_url": "https://yourname.substack.com/publish/post/148420031"
}
```

### update_draft

Change the title, subtitle, body or audience of a draft. Access: write. REST: `POST /api/v1/substack/update_draft`.

| Parameter | Type | Required | Description |
|---|---|---|---|
| `post_id` | string | yes | Post ID from list_posts. |
| `fields` | object | yes | Any of title, subtitle, body_markdown, audience. |

Changes fields of a draft and leaves the others as they are. It works on drafts only; a published post is not changed. Nothing reaches your subscribers, so it runs without asking.

Example response:

```json
{
  "post_id": "148420031",
  "status": "draft",
  "updated": [
    "title",
    "body_markdown"
  ]
}
```

### schedule_post

Publish a draft at a set time, on the web and by email. Access: write, asks the user first. REST: `POST /api/v1/substack/schedule_post`.

| Parameter | Type | Required | Description |
|---|---|---|---|
| `post_id` | string | yes | Post ID from list_posts. |
| `publish_at` | datetime | yes | ISO 8601 with time zone. |
| `send_email` | boolean | no | Email it to subscribers. Default: true. |

Schedules a draft to go live at the time you set, on the web and, unless send_email is false, by email to your subscribers. The time must be in the future. A scheduled post stays editable until it goes out. By default you confirm each call; you can switch that off for this tool.

Example response:

```json
{
  "post_id": "148420031",
  "status": "scheduled",
  "publish_at": "2026-10-13T08:00:00-04:00",
  "audience": "everyone",
  "url": "https://yourname.substack.com/p/notes-on-pricing"
}
```

### publish_post

Publish a draft now. Access: write, asks the user first. REST: `POST /api/v1/substack/publish_post`.

| Parameter | Type | Required | Description |
|---|---|---|---|
| `post_id` | string | yes | Post ID from list_posts. |
| `send_email` | boolean | no | Email it to subscribers. Default: true. |

Publishes a draft immediately, on the web and, unless send_email is false, by email to your subscribers. A sent email cannot be recalled. By default you confirm each call; you can switch that off for this tool.

Example response:

```json
{
  "post_id": "148420031",
  "status": "published",
  "published_at": "2026-10-11T10:02:00Z",
  "emailed": true,
  "url": "https://yourname.substack.com/p/notes-on-pricing"
}
```

### publish_note

Short post in Substack Notes, now or at a set time, optionally with a link card to one of your posts. Access: write, asks the user first. REST: `POST /api/v1/substack/publish_note`.

| Parameter | Type | Required | Description |
|---|---|---|---|
| `body` | string | yes | Note text, up to 1,000 characters. |
| `link_post_id` | string | no | Attach one of your posts as a card. |
| `publish_at` | datetime | no | ISO 8601 with time zone. Omit to post now. |

Posts a Note under your name. Without publish_at it goes out now; with it, the Note waits in your scheduled Notes and goes out at that time. Text is up to 1,000 characters. By default you confirm each call; you can switch that off for this tool.

Example response:

```json
{
  "note_id": "n_5521098",
  "status": "published",
  "published_at": "2026-10-11T10:05:00Z",
  "url": "https://substack.com/@yourname/note/c-5521098"
}
```

### reply_to_comment

Reply as you under a comment on your post. Access: write, asks the user first. REST: `POST /api/v1/substack/reply_to_comment`.

| Parameter | Type | Required | Description |
|---|---|---|---|
| `comment_id` | string | yes | Comment ID from list_comments. |
| `body` | string | yes | Reply text. |

Posts a reply under one comment, under your name, visible to everyone who can read the post. The author gets Substack's usual reply notification. By default you confirm each call; you can switch that off for this tool.

Example response:

```json
{
  "comment_id": "c_90432",
  "parent_id": "c_90417",
  "created_at": "2026-10-11T10:07:00Z"
}
```

### add_subscriber

Add an email as a free subscriber or give a complimentary paid plan. Access: write, asks the user first. REST: `POST /api/v1/substack/add_subscriber`.

| Parameter | Type | Required | Description |
|---|---|---|---|
| `email` | string | yes | Subscriber email. |
| `plan` | enum | no | free or comp. Default: free. |
| `comp_until` | date | no | End of the complimentary plan. |

Adds one email to your list. Substack sends the new subscriber its usual welcome email. With plan set to comp the person gets a complimentary paid plan until comp_until; for someone who already pays, the time is added after their current billing cycle. Add only people who agreed to hear from you. By default you confirm each call; you can switch that off for this tool.

Example response:

```json
{
  "email": "maya@example.com",
  "plan": "free",
  "status": "added",
  "joined_at": "2026-10-11T10:09:00Z"
}
```

## How do I connect Substack to Claude Code, Codex or Cursor?

Connecting Substack takes three steps: request access, sign in to Substack once, then add one MCP server or call the REST API with the same key.

### Connect Substack to your agent.

1. **Create an account** Sign up and add Substack in the console. Your API key is there too.

2. **Sign in to Substack once** Open the connect page from the console and sign in to Substack the way you always do. We keep the session, never your password, and you can revoke it anytime.

3. **Add Cotlet to your agent** Paste the snippet for your client. The same server and key serve every app you connect, so you do this once.

   Claude Code:

```
claude mcp add --transport http cotlet \
  https://cotlet.dev/mcp/v1 \
  --header "Authorization: Bearer $COTLET_API_KEY"
```

   Cursor:

```
{
  "mcpServers": {
    "cotlet": {
      "url": "https://cotlet.dev/mcp/v1",
      "headers": {
        "Authorization": "Bearer ${COTLET_API_KEY}"
      }
    }
  }
}
```

   Codex:

```
# ~/.codex/config.toml
[mcp_servers.cotlet]
url = "https://cotlet.dev/mcp/v1"
bearer_token_env_var = "COTLET_API_KEY"
```

4. **Ask your agent** Ask in plain words. Your agent finds the Substack tools on the server and calls them for you; anything that reaches other people waits for your OK unless you switch that off for a tool.

```
Turn essay.md into a Substack draft for everyone, schedule it for Tuesday 8:00 New York time, and schedule a Note with a link card to it for 12:00 the same day.
```

### Call Substack from your scripts.

1. **Export your API key** Your scripts use the same API key as your agent. Keep it in an environment variable, never in your code.

```
export COTLET_API_KEY="cotlet_..."
```

2. **Call a tool** Every tool is a POST endpoint at /api/v1/substack/{tool}. Send its parameters as JSON, exactly as listed in the endpoints above.

```
curl https://cotlet.dev/api/v1/substack/schedule_post \
  -H "Authorization: Bearer $COTLET_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"post_id":"148420031","publish_at":"2026-10-13T08:00:00-04:00","send_email":true}'
```

3. **Read the result** You get plain JSON back, ready for your script. A failed call costs nothing.

```
{
  "post_id": "148420031",
  "status": "scheduled",
  "publish_at": "2026-10-13T08:00:00-04:00",
  "audience": "everyone",
  "url": "https://yourname.substack.com/p/notes-on-pricing"
}
```

## Why use Cotlet for Substack?

**Built for agents**

- One MCP server for every app you connect.
- The same tools as a REST API for scripts and cron jobs.
- Works with Claude Code, Codex and Cursor.

**Your login stays yours**

- You sign in to Substack yourself. We keep only the session, encrypted with AES-256.
- The model never sees a login.
- No stored passwords, no CAPTCHA solving, no MFA bypass.

**You stay in control**

- Pick read only, or read and write.
- Anything that reaches other people waits for your OK, unless you switch it off per tool.
- Revoke access in one click.

**Kept working for you**

- We test every integration daily.
- When Substack changes, the tool pauses until we fix it.
- Failed calls cost nothing.

## Is there a Substack MCP server on GitHub?

Yes. Community Substack MCP servers exist on GitHub, usually maintained by one person. You install one on your own computer, give it a session cookie copied from your browser, and keep it running yourself; when Substack changes its site, it stops working until you or the maintainer fix it. Cotlet hosts the same kind of server for you, and our team keeps it working.

|  | GitHub MCP server | Cotlet |
|---|---|---|
| Setup | Clone the repo, copy a session cookie from DevTools into a config file, add it to each MCP client | Request access, sign in to Substack once, add one MCP server or API key |
| When Substack changes | It breaks until you or the maintainer fix it | Our team tests it daily and fixes it for you; failed calls are free |
| Your Substack session | A cookie in a file on your computer, readable by any program you run | Encrypted in an EU vault, limited to the actions you allow, revoked in one click |
| When the session expires | Tools fail until you paste a new cookie | We keep it alive; if Substack logs you out, your agent gets a link to sign in again |
| Upkeep | You update, monitor and debug it yourself | Nothing to host or update |
| Where it runs | Your computer, while it is on | Hosted: Claude Code, Codex, Cursor, n8n and scripts, also on a schedule |
| Price | Free, paid for with your time | Free 7-day trial with 5,000 credits, then credits per call |

### Which one fits you

**Pick Cotlet if**

- you are not a developer, or you do not want to maintain a server
- you need it to keep working when Substack changes, without checking it yourself
- your agent or a script should run it on a schedule, also while your computer is off

**Pick an open-source server if**

- you are comfortable installing, updating and fixing it yourself
- you want the session to stay on your own computer
- you only need it now and then, from one MCP client

## How much does the Substack API cost?

Free 7-day trial with 5,000 credits, no card needed. After that, the Substack API comes with the Cotlet plan, from $29 a month for 3,000 credits, with no limit on apps. Each month's credits stay valid for 3 months, so unused credits add up.

| Size | Price | Credits / month | Per credit |
|---|---|---|---|
| Solo | $29/mo | 3,000 | about $0.0097 |
| Pro | $99/mo | 12,000 | about $0.0083 |
| Agency | $299/mo | 40,000 | $0.0075 |

Each successful call uses credits for the work it takes; failed calls and timeouts cost nothing. A hard spend cap is on by default. Authenticate with the `Authorization: Bearer` header. [See full pricing](https://cotlet.dev/pricing)

## How Cotlet holds your access

Cotlet hosts MCP servers and REST APIs for apps with no usable API. Your agent works in your own Substack account.

- **Company details:** The legal name, address and registration numbers of the company behind Cotlet are in the Terms of service. [Terms](https://cotlet.dev/terms)
- **Your session:** You sign in to Substack yourself, in your browser. We keep only the session, never your password: encrypted with AES-256 in an EU vault, isolated to your account and used only when your agent calls a Substack tool you allowed. When it expires, your agent gives you a link to sign in again. [Security](https://cotlet.dev/security)
- **Revoking access:** Disconnect Substack in your dashboard: the session is deleted and access ends at once. Actions that reach other people wait for your OK unless you switch that off per tool.
- **What we never do:** Store passwords, solve CAPTCHAs or bypass MFA.
- **Substack's terms:** You use your own Substack account and stay responsible for following Substack's terms. Cotlet is independent and not affiliated with Substack. [Terms](https://cotlet.dev/terms)
- **Contact:** Questions about the company, security or an app: [contact@cotlet.dev](mailto:contact@cotlet.dev)

## Frequently asked questions

**How do I get access?**

Request access and pick Substack. Cotlet reviews each request and emails you your API key.

**Do I need to be technical?**

No. You sign in to Substack once in your browser and paste one command into your agent, or one URL into n8n. Your agent can walk you through it. There is no server to install, update or fix.

**Is a hosted server safe? My Substack session would leave my computer.**

Cotlet keeps your Substack session encrypted with AES-256 in an EU vault, isolated to your account and used only for the tools you allow: read only, or read and write. The AI model never sees it, and you revoke it in one click. A local server keeps the same session in a file on your computer, readable by any program you run, and needs a fresh sign-in whenever it expires.

**Can it schedule Notes as well as posts?**

Yes. publish_note takes a publish_at time and the Note waits in your scheduled Notes until then. Substack added Notes scheduling in its apps; see On Substack, linked in the sources.

**Does it need a paid Substack plan?**

It acts as the Substack account you sign in with and can do what that account can do in the publication.

**Can my agent post or send messages in Substack without asking me?**

No. Every call to schedule_post, publish_post, publish_note, reply_to_comment or add_subscriber waits for your OK by default. For scheduled automations you can switch confirmation off per tool in your dashboard, for example only for approvals. create_draft, update_draft runs without asking, because it sends nothing to anyone and one call undoes it.

**Can I use the Substack API in n8n?**

Yes. Add https://cotlet.dev/mcp/v1 with your API key in n8n's MCP Client node, or call https://cotlet.dev/api/v1/substack/{tool} from the HTTP Request node.