Inputs:

• title (string): Title of the post
• subtitle (string): Subtitle of the post
• body (string): Body of the post. Plain text becomes one paragraph per line — Markdown is not interpreted, so ## Heading arrives literally. A JSON string of a Substack document also works and is validated against the same schema set_post_body publishes, so an unrecognised node name is an error rather than a silently mangled post.

Returns: {draft_id, is_published}. Pass draft_id to get_draft to read the draft back.

For anything structured — headings, lists, links, code, images, a paywall — use set_post_body after creating the draft: the schema is published there, so the calling model can read the node vocabulary rather than guess at it.

Exposes the same filtering the Subscribers dashboard offers: 48 columns, 18 operators, free-text search, sorting and pagination.

Inputs:

• filters (array, optional): conditions combined with AND, each {column, operator, value}
• search (string, optional): free text matched against subscriber name and email
• sort_by (string, optional): any filterable column
• sort_direction (asc | desc, optional): defaults to desc
• limit (number, optional): 1–100, defaults to 25
• offset (number, optional): for paging

Which operators a column accepts depends on its type:

The columns cover subscriber identity (name, email, country, state, group membership), subscription (type, start/expiry/cancel dates, revenue, Stripe plan, attribution), email engagement (opens and unique opens over 7d/30d/6mo, links clicked, sections) and site engagement (post views, unique posts seen, comments, shares, days active, activity rating). The full list with types reaches the client in the tool's JSON Schema, so a model does not have to guess names.

Returns: {count, returned, limit, offset, subscribers}. count is the total matching the filters regardless of limit, so a call with limit: 1 is a cheap way to size a segment.

Note: engagement columns can be filtered on here but are not part of the records this tool returns — Substack takes the fields it returns from the publication's saved Display settings and ignores a per-request column list. Use export_subscribers to read their values.

There is no OR and no nesting: anything needing OR has to be issued as separate calls.

The way to actually read the engagement metrics list_subscribers can only filter on: email opens over 7d/30d/6mo, unique emails seen, post views, unique posts seen, comments, shares, links clicked, days active and activity rating.

Inputs:

• filters (array, optional): the same conditions as list_subscribers, combined with AND
• search (string, optional): free text ma

... View full README on GitHub