Erd Editor vs Substack MCP Server
A side-by-side look at the Erd Editor and Substack MCP Server MCP servers: transport, auth, tools, quality signals, and the config to install either one in Claude, Cursor, Windsurf or VS Code.
Verdict: choose Erd Editor for developer tools work as a local process; choose Substack MCP Server for developer tools as a local process. You can also run both side by side in one mcpServers block.
Which MCP server should you choose?
Choose Erd Editor when
- You need dedicated capabilities in the Developer Tools domain.
- You prefer a local stdio subprocess transport.
- Its auth model fits you: No auth required.
- You want tools like
erd_list_documents, erd_open_document, erd_save.
Choose Substack MCP Server when
- You need dedicated capabilities in the Developer Tools domain.
- You prefer a local stdio subprocess transport.
- You have the keys it needs:
SUBSTACK_PUBLICATION_URL, SUBSTACK_SESSION_TOKEN, SUBSTACK_USER_ID. - You want tools like
create_draft_post, set_post_body, upload_image.
Feature & specification comparison
Rows where the two servers differ are marked.
| Spec | ||
|---|---|---|
| Category | Developer Tools | Developer Tools |
| Quality signal | 71/100 · Great | 67/100 · Great |
| Install command | Confirmed | Confirmed |
| Transport | Local subprocess (stdio) | Local subprocess (stdio) |
| Auth | No auth required | Not declared |
| Pricing | Free | Not declared |
| Required env vars | None listed | SUBSTACK_PUBLICATION_URLSUBSTACK_SESSION_TOKENSUBSTACK_USER_ID |
| Verified owner | Community listing | Community listing |
| GitHub stars | 1,730 | 90 |
| Directory activity | 1 views 0 installs 0 upvotes | 2 views 0 installs 0 upvotes |
| Tools | 77 | 27 |
| Full listing | View Erd Editor | View Substack MCP Server |
Tools & capabilities
Erd Editor tools 77
erd_list_documentsLists ERD documents with path, open, active, dirty and readonly. With an editor serving the working directory (the VS Code extension, the Obsidian plugin or the JetBrains IDE plugin) it lists that editor's, every open project's in a JetBrains IDE; otherwise the ERD files under the working directory.erd_open_documentOpens a document for editing, in the ERD editor of the editor that serves it, if one does (the VS Code extension, the Obsidian plugin or the JetBrains IDE plugin). With create it makes the file first if missing; a name with no extension gets .erd.json.erd_saveSaves a document an editor holds to disk. VS Code keeps edits unsaved until this is called; Obsidian and JetBrains IDEs save them as they save the user’s edits, and this writes them at once. On disk, with no editor, edits are written at once and this does nothing.erd_undoReverts the last edit this agent made to the document, never the user’s edits. Calls that made no undo entry are skipped and named.erd_redoApplies again the edit erd_undo last reverted.erd_readReads a document as a snapshot, as DDL, as its raw JSON or, with the scripts format, its before and after scripts alone. The sql format of the whole document includes the document's before and after scripts. The sql format with tableIds, tableNames or groupNames gives the DDL of just those tables, the way to read a large schema; a read too large for one answer is refused with how to narrow it. For ids and details prefer erd_list and erd_get. Change a document only through the erd_ tools, never by writing its file.erd_listLists a document: its settings and counts, then a page of tables, each with its id, position and size on the ERD canvas (the width approximate, the height exact), with their indexes and relationships (each relationship once, with one of its tables) and, for a table in a table group or with a logical name, its groupId or logicalName; after the tables come the table groups, the memos, then the rows of the domain, term and word dictionaries, each with its name and what it gives a physical name or column. A small schema fits in one page. On a larger one, nextOffset and note say how to go on: query finds tables by a word, namesOnly lists every table name in a call or a few. Columns, comments, memo text, the tables of a group and every field of a dictionary row come from erd_get; the foreign keys a table holds, from erd_read sql with tableNames.erd_getGives the entities named, in full: tables with their columns and size, relationships with their columns, indexes with their columns, memos with their text, table groups with their tables, and words, terms and domains with every field. Ids and names that name nothing live are listed in missing; ids one answer has no room for are listed in notReturned, to ask for again.erd_list_checksLists what the word, term and domain dictionaries find, as the Checks sheet of the editor's Dictionary tab does, and changes nothing. Errors: a name two rows of one dictionary share, a link to a domain the document does not list, a forbidden word in a logical name or a term's name. Warnings: a word no dictionary lists, a synonym used for a standard word, each in a logical name or a term's name, a physical name other than the one the term of its logical name gives, a column type other than its domain's. Each check names its target (a table, a column with its table, or a word, term or domain row) with its names, the field read, the text found and, where the dictionaries have them, the suggestions to use instead, and counts gives each code's total. The words, terms and domains come first in sheet order, then each table and its columns in document order. With no dictionary row nothing is checked. A long list comes a page at a time: pass nextOffset, or list again from offset 0 after fixing some, since a fixed check leaves the list.erd_add_tableAdds an empty table at a free spot and returns its id in createdIds. Name it with erd_change_table_name.erd_remove_tableRemoves a table with its columns, indexes and every relationship that touches it.erd_change_table_nameRenames a table. The name is then its own: nameDerived goes off, so a later logical name leaves a name that is not empty as it is.- +65 more on the listing page
Substack MCP Server tools 27
create_draft_postcreate a draft post on your Substack account.set_post_bodyreplace the body of a draft with a Substack document. This is the only way to write structured content — headings, lists, links, code blocks, images, buttons and a paywall. Create the draft first with create_draft_post, then call this with its id. The result reports how many nodes of each type were stored, so a caller can confirm that what it asked for is there. An image must already be hosted by Substack: this cannot upload one.upload_imageHost an image on your Substack publication and get back a Substack URL — the one thing image2.src in set_post_body and cover_image in update_draft will actually render. The source is either an http(s) URL, which the server downloads and re-hosts, or `path`, an absolute path to a local file on the machine running this server, which is read straight from disk: use that for an image you generated or edited locally, with no need to publish it anywhere first. Private and loopback hosts are refused, HEIC is not accepted, max 10 MB.list_subscribersList and filter the subscribers of your Substack publication. Supports the same 48 columns and operators as the Subscribers dashboard, combined with AND, plus free-text search, sorting and pagination. Returns `count`, the total matching the filters regardless of `limit`, so a call with limit 1 is a cheap way to size a segment. Engagement columns (email opens, post views, comments, shares, activity rating) can be filtered on here but are not part of the records this tool returns — use export_subscribers to read their values.export_subscribersExport subscribers with their full column values, including the engagement metrics list_subscribers can filter on but not return: email opens over 7d/30d/6mo, unique emails seen, post views, unique posts seen, comments, shares, links clicked, days active and activity rating. Takes the same filters as list_subscribers and covers the whole matching set — there is no paging. Substack generates the file asynchronously, so this waits for it and returns the parsed records. One column cannot be exported and is reported in `missing_columns` rather than failing: tag_ids.list_postsList the posts of your Substack publication: drafts, published posts or scheduled posts. Supports free-text search, pagination and sort direction. Each post is returned as a summary; use get_draft for the full content of an unpublished one.get_draftRead one draft post of your Substack publication in full, including its body and its audience and email settings. Take the id from list_posts or create_draft_post.update_draftChange an existing draft's title, subtitle or any of its Post settings: audience, who may comment, comment order, cover image, social preview title and description, SEO title and description, and URL slug. The update is partial: only the fields you pass change, everything else — including the body — is left alone. A cover_image not already hosted by Substack is downloaded and re-hosted first. Take the id from list_posts or create_draft_post.publish_draftPublish a draft. The post goes live on the web; `send` additionally emails it to subscribers and defaults to false, because an email cannot be recalled. Publishing cannot be undone from this server — there is no unpublish tool.delete_draftDelete an unpublished draft. Refuses if the id belongs to a published post: Substack deletes both through the same endpoint, and removing a live post is irreversible, so that is left to the dashboard.get_publicationRead the settings and identity of your Substack publication: name, subdomain, custom domain, hero text, copyright, sender name, logo, plans and payment state. Returns a projection by default; pass full: true for all 111 fields.get_user_profileRead the account behind the session: id, handle, name, bio, and every publication you have a role on. This is how to discover which publications the session can reach, beyond the one SUBSTACK_PUBLICATION_URL points at.- +15 more on the listing page
Ready-to-paste client configs
Paste either block (or both) into your client config, e.g. claude_desktop_config.json or ~/.cursor/mcp.json. We only show a config when the install command is confirmed.
Erd Editor
{
"mcpServers": {
"erd-editor": {
"command": "npx",
"args": [
"-y",
"@dineug/erd-editor-mcp"
]
}
}
}
Substack MCP Server
{
"mcpServers": {
"substack-mcp-server": {
"command": "npx",
"args": [
"-y",
"substack-mcp@latest"
],
"env": {
"SUBSTACK_PUBLICATION_URL": "YOUR_SUBSTACK_PUBLICATION_URL_HERE",
"SUBSTACK_SESSION_TOKEN": "YOUR_SUBSTACK_SESSION_TOKEN_HERE",
"SUBSTACK_USER_ID": "YOUR_SUBSTACK_USER_ID_HERE"
}
}
}
}
Frequently asked questions
Erd Editor is categorized under Developer Tools and uses a local stdio subprocess. Substack MCP Server belongs to Developer Tools and uses a local stdio subprocess. Pick Erd Editor for developer tools work and Substack MCP Server for developer tools.
Copy the mcpServers block from the config section on this page into your client's config (for example claude_desktop_config.json or ~/.cursor/mcp.json), then fully restart the client.
Erd Editor is listed as free. Auth: no auth required. Substack MCP Server has no declared pricing — check the project's own site. If a server needs environment variables such as API keys, define them under the env key in your client's MCP config.
Yes. MCP clients support multiple servers: add erd-editor and substack-mcp-server as separate keys in the same mcpServers object, and your assistant will call tools from either one.
On AllMCPs, Erd Editor has a quality signal of 71/100 (Great) with 1 views, 0 installs and 1,730 GitHub stars. Substack MCP Server has 67/100 (Great) with 2 views, 0 installs and 90 GitHub stars.